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<< Robbins And Cotran Pathologic Basis Of Disease 9th Edition By Kumar Abbas Test Bank | International Economics 3rd Edition By Robert C. Feenstra Test Bank >> |

**Chapter 02**

**The Scientific Method**

**Short Answer Questions**

*(p. 29-31)*How is the empirical approach that is used in the scientific method different from a nonscientific (everyday) approach to knowledge?

The empirical approach involves the use of evidence based on direct observation and experimentation to determine what is true. A nonscientific (everyday) approach relies primarily on intuition and casual (unsystematic) observation to decide what is true.

*Level: Factual
*

*(p. 38)*Distinguish between the reliability and the validity of a measurement and provide an example of a reliable measurement that may not be valid.

The reliability of a measure is indicated by its consistency; for example, when observers agree in their observations, the measurement is said to be reliable. Validity refers to the truthfulness of a measurea valid measure of a construct measures what it claims to measure. An example of a reliable measure that may not be valid is a scale that provides the same weight each time a person steps on it, but is five pounds off. Another example is from research which indicates that raters agree on their ratings of trustworthiness when judging photos of individuals (reliability), but those ratings were unrelated to whether students cheated on a test (not valid).

*Level: Factual
*

*(p. 42-44)*Distinguish between the nomothetic approach and the idiographic approach in descriptions of psychological phenomena.

The nomothetic approach is used to seek broad generalizations and universal laws (i.e., what in general is true) by studying large numbers of participants of a group and focusing on the average performance of the group. The idiographic approach is used to focus on the uniqueness of the individual by studying an individual intensively using single-case research.

*Level: Factual
*

*(p. 47-48)*Explain how an experiment is used to understand the cause of a phenomenon by describing the three conditions for causal inference an experiment meets.

Researchers conduct an experiment when they manipulate an independent variable and observe the effects of the manipulation on a dependent variable measure. When differences on the dependent variable are observed for the conditions of the independent variable, covariation is met (i.e., different scores on the dependent variable covary with different conditions of the independent variable). In addition, because differences on the dependent variable are observed after the independent variable manipulation, the second condition for causal inference-time-order relationship-is met. When the experiment is free of confoundings the researcher is able to eliminate alternative explanations for the outcome, the third condition for causal inference.

*Level: Conceptual
*

*(p. 49)*Describe the differences between basic and applied research.

In basic research the research psychologist seeks primarily to understand behavior and mental processes. Basic research is typically carried out in a laboratory using controlled experiments and is usually done with the goal of testing a theory about behavior. It is, in a sense, seeking knowledge for its own sake. Applied research is conducted in order to improve peoples lives and often is carried out in nonlaboratory settings (e.g., schools, workplaces). Applied research often builds upon findings from basic research; these findings are applied in natural settings with the scientific goal of creating change.

*Level: Factual
*

**Multiple Choice Questions**

*(p. 29)*Peoples tendency to select news programs that do not challenge their attitudes or beliefs is explained by

A. hypothesis testing.

confirmation bias.__B.__

C. controlled observation.

D. a skeptical attitude.

*Level: Applied
*

*(p. 29)*Which of the following is a cognitive error that can cause confirmation bias because we perceive a relationship when none exists?

A. subjective reporting

B. covariation of cause and effect

C. spurious relationship

illusory correlation__D.__

*Level: Factual
*

*(p. 30)*The empirical approach emphasizes

direct observation and experimentation.__A.__

B. intuition and skepticism.

C. reliability and confirmation.

D. control and qualitative analysis.

*Level: Factual
*

*(p. 30)*Which of the following is a characteristic of the scientific method?

A. confirmation bias

B. intuitive definitions

systematic observation__C.__

D. circular hypotheses

*Level: Conceptual
*

*(p. 30)*As an approach to knowledge, the scientific method relies on

A. intuitive hypotheses.

B. subjective measurement.

empirical procedures.__C.__

D. deductive theorizing.

*Level: Factual
*

*(p. 30)*The essential ingredient of scientific observation is

A. precise measurement.

control.__B.__

C. prediction.

D. application.

*Level: Factual
*

*(p. 31-32)*The primary means scientists use to establish control in their observations is to

systematically manipulate an independent variable in an experiment.__A.__

B. train multiple observers.

C. establish the accuracy and precision of their measurements.

D. observe many dependent variables.

*Level: Factual
*

*(p. 32)*Based on investigations with the horse Clever Hans, an important factor researchers should seek to control when testing whether dogs can sniff cancer in urine samples is

A. whether the dogs are tested indoors or outdoors.

B. that some samples should come from people and some from horses.

C. that the urine samples should come from a diverse group of patients.

whether, during testing, the dogs can see people who know which samples came from cancer patients.__D.__

*Level: Conceptual
*

*(p. 32)*The factors that the researcher controls or manipulates in order to determine their effect on behavior are called the

A. relevant variables.

independent variables.__B.__

C. intervening variables.

D. dependent variables.

*Level: Factual
*

*(p. 32)*In a study investigating the effects of two different types of music on students test performance, the music represents the

independent variable.__A.__

B. intervening variable.

C. dependent variable.

D. applied variable.

*Level: Applied
*

*(p. 32-33)*In an experiment that compares aggressive responses following exposure to media violence (present, absent) in television programming, aggressive responses is the __________ and exposure to media violence is the __________.

A. construct; operational definition

B. operational definition; construct

C. independent variable; dependent variable

dependent variable; independent variable__D.__

*Level: Applied
*

*(p. 33)*In a study examining the number of proofreading errors make when students are tested while reading under bright or dim lighting, the number of proofreading errors represents the

A. control variable.

B. intervening variable.

dependent variable.__C.__

D. independent variable.

*Level: Applied
*

*(p. 33)*The term scientists use to refer to a psychological concept is

construct.__A.__

B. validity.

C. variability.

D. operational definition.

*Level: Factual
*

*(p. 34)*An operational definition of a construct is

A. an intervening variable that connects independent and dependent variables.

a specific procedure for producing or measuring the construct.__B.__

C. reliable, because it is consistent.

D. valid, because it is truthful.

*Level: Factual
*

*(p. 34)*When intelligence is defined using a paper-and-pencil test that emphasizes understanding of logical relationships and familiarity with the meaning of words, intelligence is being defined with

A. a construct definition.

B. a hypothetical definition.

C. a conceptual definition.

an operational definition.__D.__

*Level: Applied
*

*(p. 34)*Which of the following characteristics is most assured when scientists use operational definitions to communicate?

A. reliable measurement

B. meaningfulness

clarity of meaning__C.__

D. valid measurement

*Level: Conceptual
*

*(p. 35)*One disadvantage that results from the use of operational definitions is that

A. the reliability and validity of the operational definition become equivalent.

B. the number of psychological constructs becomes smaller.

C. communication among scientists becomes confused.

a potentially limitless number of operational definitions exists for any construct.__D.__

*Level: Conceptual
*

*(p. 35)*When scientists report their findings they strive to describe

only what they have observed.__A.__

B. only their inferences about behavior.

C. what they have observed along with their inferences.

D. only aspects of what they have observed that differ from what they expected to observe.

*Level: Factual
*

*(p. 35-36)*Suppose you come across a car accident at an intersection and observe that a small car is severely damaged and a large SUV appears to have only a headlight broken. If you describe the accident as occurring because the SUV hit the smaller car, your report likely includes

A. contaminated observations.

inferences.__B.__

C. distorted behaviors.

D. illusory correlations.

*Level: Applied
*

*(p. 36)*Which of the following is an accepted check that scientists can use to determine whether a scientific report is unbiased?

A. the precision of the data that are reported

B. parsimony of explanation

C. clear operational definitions

agreement between observers__D.__

*Level: Factual
*

*(p. 36)*A researcher calibrates an instrument by placing a five-pound weight on a scale to see if the scale gives a reading of 5.0 pounds. The researcher is testing the scales

A. reliability.

B. validity.

accuracy.__C.__

D. correlation.

*Level: Applied
*

*(p. 36)*A student sets a computer program to record participants responses to materials in her experiment to the millisecond, rather than to the tenth of a second. Which characteristic of the measuring instrument is the student trying to ensure?

A. accuracy

precision__B.__

C. validity

D. reliability

*Level: Applied
*

*(p. 37)*The main difference between physical measurement and psychological measurement is that*physical measurement*

A. uses humans as the measurement instruments.

B. requires multiple observers to assess agreement.

involves dimensions with agreed-upon standards and instruments.__C.__

D. is quantitative and nomothetic.

*Level: Factual
*

*(p. 37)*When using psychological measurement of a dimension such as aggression, psychologists often base their measurements of peoples aggressiveness on

agreement among a number of observers regarding their ratings of behavior on an aggressiveness scale.__A.__

B. consensus among researchers in the field of aggression as to the theoretical definition of aggression.

C. consistency across operational definitions of aggression.

D. availability of a precise measuring instrument, preferably based on a physiological response.

*Level: Factual
*

*(p. 38)*A new measure of intelligence (e.g., speed of processing spatial distances) would be a valid measure of intelligence if scores on the new measure were

A. unrelated to scores on other accepted measures of intelligence.

B. more varied across people than scores on other accepted measures of intelligence.

C. more precise than scores on other accepted measures of intelligence.

related to scores on other accepted measures of intelligence.__D.__

*Level: Factual
*

*(p. 38)*An individuals score on a test such as the SAT represents how that person consistently performs on such a test only if the SAT test is a _____________ measure.

A. precise

reliable__B.__

C. valid

D. standardized

*Level: Applied
*

*(p. 38)*Researchers are more likely to achieve reliable observations when

A. one observer has spent a long time observing an event.

B. one observer reports having observed a very unusual event.

C. two observers provide unique descriptions of an event.

two observers show agreement in their descriptions of an event.__D.__

*Level: Factual
*

*(p. 38)*Research suggests that when judging photos of peoples faces, people demonstrate high levels of agreement regarding which faces appear trustworthy, but that these ratings dont correspond to whether the people in the photos are guilty or innocent of cheating on a test. This finding indicates that measurements can be __________, yet not ___________.

reliable; valid__A.__

B. precise; accurate

C. nomothetic; idiographic

D. basic; applied

*Level: Applied
*

*(p. 38)*Reliability refers to the ________ of measurement, and validity refers to the ________ of measurement.

A. calibration; trustworthiness

B. accuracy; precision

consistency; truthfulness__C.__

D. testability; parsimony

*Level: Factual
*

*(p. 38)*A researcher develops a brief questionnaire measure of peoples level of optimism. To determine whether his measure is a good one, he asks a sample of people to complete his questionnaire twice, separated by one month. At the second session, he also asks his participants to complete another measure of optimismone that has been an accepted measure of optimism for many years. Using this procedure, the researcher is establishing the

A. independent variable of optimism.

B. precision and accuracy of his measure.

reliability and validity of his measure.__C.__

D. nomothetic and idiographic features of optimism.

*Level: Applied
*

*(p. 38)*The testable, tentative explanations scientists use to explain events are called

A. confirmatory biases.

hypotheses.__B.__

C. heuristics.

D. causal inferences.

*Level: Factual
*

*(p. 38)*The idea that people purchase green products in order to achieve higher status by behaving altruistically is

a hypothesis.__A.__

B. a circular argument.

C. reliable and valid.

D. all of these

*Level: Factual
*

*(p. 39)*What characteristic distinguishes scientific hypotheses from casual, everyday hypotheses?

A. certainty

B. intuitive appeal

testability__C.__

D. circularity

*Level: Factual
*

*(p. 40)*A researchers hypothesis predicts that people are more aggressive following exposure to media violence because they find the violence disturbing. A potential problem with this hypothesis is

the concept disturbing is not adequately defined.__A.__

B. it appeals to forces not recognized by science.

C. it is circular: aggression and disturbing refer to the same thing.

D. all of these

*Level: Applied
*

*(p. 40)*Scientists would likely reject the hypothesis that a person was violent because the person was possessed by the Devil. Scientists reject a hypothesis like this one not because it is inherently wrong, but because the hypothesis lacks the necessary scientific characteristic of being

A. complex.

B. circular.

C. concise.

testable.__D.__

*Level: Factual
*

*(p. 40)*When an hypothesis is stated in such a way that the event to be explained becomes the explanation itself (e.g., the child is distractable because he has attention deficit disorder), the hypothesis is said to be

A. inadequately defined.

circular.__B.__

C. appealing to forces not recognized by science.

D. redundant.

*Level: Factual
*

*(p. 40)*Four goals of research in psychology are

A. reliability, validity, experimentation, and theory construction.

description, prediction, explanation, and application.__B.__

C. description, correlation, experimentation, and theory construction.

D. observation, measurement, causal inference, and explanation.

*Level: Factual
*

*(p. 40)*The criteria used to classify and define mental disorders in the*Diagnostic and Statistical Manual of Mental Disorders*represent an illustration of which of the following goals of the scientific method?

description__A.__

B. prediction

C. explanation

D. therapy

*Level: Factual
*

*(p. 42)*Using the nomothetic approach, psychologists seek to

A. describe one individuals behavior in relation to his or her environment.

B. create change in an individuals life.

C. eliminate confoundings in their experiments.

establish general laws of behavior that apply to a diverse population.__D.__

*Level: Factual
*

*(p. 42-43)*The nomothetic approach in psychology (or in any science) is intended to establish broad generalizations and universal laws. When using the nomothetic approach researchers are likely to make

A. many observations of one individual.

B. observations of many individuals and focus on extreme scores.

observations of many individuals and focus on the average (typical) score.__C.__

D. few observations of a few individuals and focus on the scores that occur most often.

*Level: Conceptual
*

*(p. 42-43)*A cross-cultural study that examined helping behaviors in 23 large cities around the world found that, in general, people in Rio de Janeiro were most helpful and people in Kuala Lampur were least helpful. From these findings, we know that

A. everyone in Rio de Janeiro is more helpful than everyone in Kuala Lampur.

B. there are more people in Rio de Janeiro than in Kuala Lampur.

C. any one individual we choose in Rio de Janeiro will be helpful.

none of these__D.__

*Level: Conceptual
*

*(p. 43)*Research that focuses on describing the unique characteristics of individuals is referred to as the

A. applied method.

idiographic approach.__B.__

C. Diagnostic and Statistical Manual.

D. functional approach.

*Level: Factual
*

*(p. 43-44)*A researcher asks a sample of 200 individuals to complete a questionnaire. She then computes statistics to describe how individuals respond in general to the questions. This researchers approach is

A. idiographic and quantitative.

B. idiographic and qualitative.

nomothetic and quantitative.__C.__

D. nomothetic and qualitative.

*Level: Applied
*

*(p. 44)*Which of the following characterizes the majority of the research conducted in psychology?

quantitative research using the nomothetic approach__A.__

B. quantitative research using the idiographic approach

C. qualitative research using the nomothetic approach

D. qualitative research using the idiographic approach

*Level: Factual
*

*(p. 44)*When research consists of verbal summaries of naturally occurring, ordinary events in natural settings the research is

more likely to be qualitative research than quantitative research.__A.__

B. more likely to be quantitative research than qualitative research.

C. equally likely to be qualitative or quantitative research.

D. unlikely to be either qualitative or quantitative research.

*Level: Factual
*

*(p. 44)*Researchers interviewed 29 youth (ages 17-24) who live on the streets of Toronto about their experiences with suicide. When the researchers read transcripts of the interviews, they noticed themes of isolation and rejection. This is an example of ____________ research.

A. idiographic

B. correlational

qualitative__C.__

D. explanatory

*Level: Applied
*

*(p. 45)*A correlational study is uniquely useful for meeting which of the following goals of the scientific method?

A. description

prediction__B.__

C. explanation

D. application

*Level: Factual
*

*(p. 45)*A correlation exists when

A. two hypotheses are shown to support the same theory.

B. two independent variables are confounded.

two measures of the same people, events, or things vary together.__C.__

D. a measurement is both reliable and valid.

*Level: Factual
*

*(p. 45)*Research has indicated that amount of undergraduate research activity predicts measures of later success in the profession of psychology. For this prediction to be possible, undergraduate research activity and later success must be

A. circular.

B. qualitative.

C. causal.

correlated.__D.__

*Level: Applied
*

*(p. 45)*Correlations are valuable because they allow psychologists to

A. create change in peoples lives.

make predictions based on the way two variables covary.__B.__

C. describe, predict, and understand the causes of psychological phenomena.

D. all of these

*Level: Conceptual
*

*(p. 45)*When researchers observe a correlation between two variables, such as between the amount of time spent studying and test scores, they know that

A. the first variable causes the second variable.

B. the second variable causes the first variable.

C. both (A) and (B)

neither (A) nor (B)__D.__

*Level: Conceptual
*

*(p. 45)*Which of the following statements best describes the relationship between correlation and causation?

Correlation does not imply causation.__A.__

B. Correlation directly implies a causal inference.

C. Correlation and causation refer to the same thing.

D. Correlation is confounded with causation.

*Level: Conceptual
*

*(p. 45-46)*Researchers have shown that teacher evaluations based on brief viewings of videotapes made by students who were not enrolled in a course correlate well with end-of-the-semester teacher evaluations made by students enrolled in the class. The researchers suggest that the relationship occurs because people can make relatively accurate judgments of affective behavior (e.g., likableness) very quickly because doing so is adaptive. Based on the correlational evidence alone, the researchers explanation for their findings can best be considered

speculative.__A.__

B. qualitative.

C. a causal inference.

D. a confirmed hypothesis.

*Level: Conceptual
*

*(p. 45-46)*The research goal of prediction is most associated with _________ research, and the research goal of explanation is most associated with _________ research.

A. applied; basic

correlational; experimental__B.__

C. multimethod; single method

D. nomothetic; idiographic

*Level: Conceptual
*

*(p. 46)*Researchers demonstrated a relationship between the extent to which people in large cities help strangers and the degree of cultural embeddedness in the city (i.e., concern for family and in-group members). As cultural embeddedness increased, people were less likely to help strangers. This relationship indicates that

A. concern for family and in-group members causes people to avoid helping strangers.

B. helping strangers causes a decrease in cultural embeddedness.

C. both (A) and (B)

neither (A) nor (B)__D.__

*Level: Conceptual
*

*(p. 46)*Psychologists use ____________ to identify the causes of a phenomenon.

A. correlations

B. quantitative research

controlled experiments__C.__

D. operational definitions

*Level: Factual
*

*(p. 47)*A(n) ____________ is a statement about the cause of an event or behavior.

A. experiment

causal inference__B.__

C. construct

D. correlation

*Level: Factual
*

*(p. 47)*Which of the following is*not*one of the conditions for making a causal inference?

A. covariation of events

B. a time-order relationship

confounding of variables__C.__

D. elimination of plausible alternative causes

*Level: Factual
*

*(p. 48)*When two potentially effective independent variables are allowed to covary simultaneously, a __________ has occurred.

confounding__A.__

B. correlation

C. dependency

D. causal inference

*Level: Factual
*

*(p. 48)*A researcher wanted to compare the relative effectiveness of two techniques for reducing anxiety: a drug and a relaxation exercise. The researcher gave the experimental group both the drug and the relaxation exercise. The control group was given neither the drug nor the exercise. The difference between the drug and the relaxation exercise cannot be compared in this experiment because the experiment involves a

A. redundant relationship.

B. correlation.

C. causal inference.

confounding.__D.__

*Level: Applied
*

*(p. 48)*A researcher is interested in testing the effectiveness of using clickers for question-and-answer sessions during lectures. He asks students in the morning section of his course to use clickers to respond to in-class questions. Students in the afternoon section write answers to questions in their notebook. He compares the students average test performance for the two sections. The researcher will not be able to interpret the results because his study is flawed due to

A. his limited ability to generalize his results to other students and courses.

the confounding of class section (morning, afternoon) and response method (clicker, notebook).__B.__

C. his failure to manipulate an independent variable.

D. the correlation between response method (clicker, notebook) and test performance.

*Level: Applied
*

*(p. 49)*When scientists conduct research they seek to

A. use only real-world settings.

B. use only laboratory settings.

C. describe the findings only for people and circumstances who participated in their study.

generalize their findings beyond the people and circumstances used in their study.__D.__

*Level: Factual
*

*(p. 49)*Research that is conducted with the goals of understanding phenomena and testing a theory is referred to as __________ research.

A. correlational

B. applied

basic__C.__

D. idiographic

*Level: Factual
*

*(p. 49)*The widespread application of psychological principles in our everyday life is possible because of ___________ in the past.

basic research__A.__

B. time-order relationships

C. parsimony

D. intervening variables

*Level: Conceptual
*

*(p. 49)*Which of the following statements about research in psychology is*true*?

A. All research in psychology involves experiments.

Psychologists view basic research and applied research as complementary.__B.__

C. Researchers observe correlations between variables to make causal inferences about behavior.

D. all of these

*Level: Conceptual
*

*(p. 50-51)*A(n) __________ is a logically organized set of propositions that serves to define events, describe relationships among events, and explain the occurrence of events.

theory__A.__

B. intervening variable

C. hypothesis

D. causal inference

*Level: Factual
*

*(p. 51)*The major function of a theory in psychology is to

organize empirical knowledge and guide research.__A.__

B. derive explanations that are independent of the results of experiments.

C. formulate definitive explanations for empirical findings.

D. develop quantitative and qualitative predictions for the results of future experiments.

*Level: Factual
*

*(p. 51)*Theorists propose _______ variables to connect independent and dependent variables and explain why these variables are connected.

A. hypothetical

B. operational

C. confounding

intervening__D.__

*Level: Factual
*

*(p. 51-52)*A researcher manipulates the amount of time participants view a list of words (1*vs*. 4 minutes), and measures the number of words the participants are able to write down 10 minutes later. The researcher suggests that in-between the presentation time and the later recall of the words, the words are in participants memory. The construct of memory in this example represents

A. an operational definition.

an intervening variable.__B.__

C. the researchers independent variable.

D. the researchers dependent variable.

*Level: Applied
*

*(p. 52)*Of the following, the best description of intervening variables in psychology is that

A. there are very few intervening variables in psychology.

B. they are obstacles in successful theory construction and testing.

they are constructs that unite a wide variety of apparently dissimilar variables.__C.__

D. they rarely are of use when psychologists try to explain why variables are related.

*Level: Conceptual
*

*(p. 50, 53)*The greater the scope of a theory, the more complex it is likely to be. Complexity is

A. a serious obstacle to testing a theory.

B. a necessary characteristic of psychological theories given the nature and range of phenomena psychologists try to understand.

(A) and (B)__C.__

D. none of these

*Level: Conceptual
*

*(p. 53)*A theory that predicts children will develop abstract reasoning by age 12 is more ________ than a theory that predicts the development of abstract reasoning by ages 12 to 20.

A. general

precise__B.__

C. hypothetical

D. parsimonious

*Level: Factual
*

*(p. 53)*When constructing and evaluating a theory, scientists follow a guideline that places a premium on identifying the simplest of alternative explanations of a phenomenon. This guideline is called the

A. test of empirical verification.

B. law of least error.

C. precision of prediction.

rule of parsimony.__D.__

*Level: Factual
*

*(p. 53)*The most rigorous test of a scientific theory involves

A. precision of prediction.

B. generalization.

falsification.__C.__

D. the rule of parsimony.

*Level: Factual
*

*(p. 53-54)*A researcher conducted two experiments to test a theory. One experiment was designed to confirm a hypothesis of the theory and the second experiment was designed to falsify the hypothesis. From the perspective of theory construction and testing,

A. the theory is precise and parsimonious.

B. the theory is neither precise nor parsimonious.

C. the first experiment is more informative.

the second experiment is more informative.__D.__

*Level: Factual
*

* *

**Chapter 12**

**Data Analysis and Interpretation: Part II. Tests of Statistical Significance and the Analysis Story**

**Short Answer Questions**

*(p. 381-382)*Null hypothesis significance testing is used to compare two means in an independent groups design. (a) What is the null hypothesis? (b) What is required to reject the null hypothesis?

(a) The null hypothesis when two means are compared is that the mean of the first population is the same as the mean of the second population. (b) A statistically significant difference between two sample means is required to reject the null hypothesis. Specifically, it must be shown that there is a very low likelihood that a difference between the two sample means would occur by chance if the null hypothesis were true (i.e., *p* < .05).

*Level: Factual
*

*(p. 384)*Explain the difference between experimental sensitivity and statistical power and identify factors that influence each.

Sensitivity refers to the likelihood that an experiment will detect the effect of an independent variable when, in fact, the independent variable truly has an effect. Factors that affect error variation influence sensitivity; for example, by holding conditions constant (reducing error variation), researchers increase the sensitivity of an experiment. Power refers to the likelihood that a statistical test will allow researchers to reject correctly the null hypothesis of no group differences. The power of statistical tests is influenced by the level of statistical significance, the size of the treatment effect, and the sample size. The power of a statistical test is greater as the effect size of a treatment effect increases, and as the sample size increases.

*Level: Conceptual
*

*(p. 383, 386)*(a) What is a Type I error and what is a Type II error when using NHST? (b) Which is more common in psychological research?

(a) Decisions about the outcome of an experiment are based on probabilities. A Type I error occurs when researchers rejecting a true null hypothesis (i.e., there is no difference between population means but a difference is claimed). A Type II error occurs when researchers fail to reject a false null hypothesis (i.e., a true difference between population means is missed). (b) Type II errors are more common in psychological research because many studies have low statistical power.

*Level: Factual
*

*(p. 381-382)*What does NHST tell us when a statistically significant finding is obtained?

We know that something interesting has happened. We have obtained evidence for the fact that there is a nonzero difference between the population means and it is likely in the direction we observed with the group means in an experiment. We also know that the smaller the exact probability, the greater is the probability that an exact replication will produce a statistically significant (*p* < .05) finding.

*Level: Factual
*

*(p. 388-389)*When a result is statistically significant, why should we not immediately claim that our results are important (either scientifically or practically)?

Whether the results of a study are important to the scientific community will depend on the nature of the variable under study (the effects of some variables are simply more important than those of others), how sound is the study (statistically significant findings are easily produced with poorly done studies), and other criteria such as effect size. Similarly, the practical or clinical significance of a treatment effect depends on factors other than statistical significance. These include the external validity associated with the study, the size of the effect, and various practical considerations (including financial ones) associated with a treatments implementation. Even a statistically significant outcome showing a large effect size is not a guarantee of its practical or clinical significance. A very large effect might be obtained as a part of a study that does not generalize well from the laboratory to the real world (i.e., has low external validity); thus, the results may be of little value to the applied psychologist. Moreover, a relatively large treatment effect that does generalize well to real-world settings may never be applied because it is too costly, too difficult to implement, too controversial, or too similar in its effects to existing treatments. It is also possible that, given enough power, a small effect size will be statistically significant. Small effect sizes may not be practically important outside the laboratory.

*Level: Conceptual
*

*(p. 393-394)*Briefly describe the logic of the analysis of variance or*F*-test for a single-factor random groups design.

There are two sources of variation in any random groups experiment. First, variation within each group can be expected because of individual differences among subjects who have been randomly assigned to a group. The second source of variation in the random groups design is variation between the groups. If the null hypothesis is true (no differences among groups), any observed differences among the means of the groups can be attributed to error variation (e.g., the different characteristics of the participants in the groups). Thus, the variation among the different group means, when the null hypothesis is assumed to be true, provides a second estimate of error variation in an experiment. If the null hypothesis is true, this estimate of error variation between groups should be similar to the estimate of error variation within groups. Thus, the random groups design provides two independent estimates of error variation, one within the groups and one between the groups. The ratio of these two estimates, as represented in the *F*-test, should be 1.0.

If the null hypothesis is false, that is, the independent variable has had an effect, there will be systematic differences in the means across the different groups of the experiment. This systematic variation will be added to the differences in the group means that are already present due to error variation. By creating a ratio (*F*-ratio) of variation between groups and variation due to individual differences, evidence can be obtained regarding the likelihood of systematic variation in the experiment.

*Level: Factual
*

*(p. 396-397, 407)*Use the ANOVA Summary Table to answer the question that follow:How many levels are there for Factor A and Factor B?

Factor A has 2 levels and Factor B has 3 levels.

*Level: Applied
*

*(p. 396-397, 407)*Use the ANOVA Summary Table to answer the question that follow:What is the total number of subjects, and assuming equal group size, how many subjects are there in each group?

The total number of subjects in 42; with six conditions in this complex design there are 7 subjects per group.

*Level: Applied
*

*(p. 396-397, 407)*Use the ANOVA Summary Table to answer the question that follow:What values form the numerator and denominator for the

*F*-ratio (*F*-test) for each statistical effect?

The denominator for each *F*-test is the same, the Mean Square Error (10.25). The numerator for each test is the Mean Square associated with each effect: Factor A, 2.38; Factor B, 36.45; A B, 102.45.

*Level: Applied
*

*(p. 396-397, 407)*Use the ANOVA Summary Table to answer the question that follow:Which results are statistically significant? Explain how you arrived at this decision.

The main effect of Factor B and the interaction effect (A B) are statistically significant because the probabilities associated with these effects (.039 and .000, respectively) are less than the conventional level of significance (*p* < .05).

*Level: Applied
*

*(p. 407-408)*Use the ANOVA Summary Table to answer the question that follow:Describe the analysis that should be conducted next.

The source of the statistically significant interaction should be explored using simple main effects analyses. There are two ways this could be done: (1) the simple main effects of Factor A at each of the three levels of Factor B could be tested, or (2) the simple main effects of Factor B at each of the two levels of Factor A could be tested.

*Level: Applied
*

*(p. 381, 387)*Read the following research report and answer the question that follow.

A researcher compares mens and womens attitudes toward dating their best friends former girl/boy friend. Specifically, college students are asked to read a story describing a situation in which their best friend breaks up with a partner and they later have an opportunity to date their best friends former partner. Men and women rate the likelihood they would choose to date their best friends former partner using a 10-point scale (0 =*not at all likely*and 9 =*completely likely*). In addition, participants rate the extent to which a similar situation has occurred to them using a 10-point scale (0 =*not at all*and 9 =*completely*). The mean ratings for each question for the two groups, men and women, are presented below:Were the results statistically significant? Explain your decisions.

The difference in ratings between men and women for the question regarding likelihood of dating was statistically significant because the probability associated with the *t*-statistic (.01) is less than the conventional level of significance (*p* < .05). In contrast, the difference in ratings between men and women for the question regarding the similarity of the situation was not statistically significant because .08 is greater than .05.

*Level: Applied
*

*(p. 381, 387)*Read the following research report and answer the question that follow.

A researcher compares mens and womens attitudes toward dating their best friends former girl/boy friend. Specifically, college students are asked to read a story describing a situation in which their best friend breaks up with a partner and they later have an opportunity to date their best friends former partner. Men and women rate the likelihood they would choose to date their best friends former partner using a 10-point scale (0 =*not at all likely*and 9 =*completely likely*). In addition, participants rate the extent to which a similar situation has occurred to them using a 10-point scale (0 =*not at all*and 9 =*completely*). The mean ratings for each question for the two groups, men and women, are presented below:How many men and women were there in this study (assuming equal numbers of men and women)?

We know there were 30 participants total because the *df* are 28; thus, there were 15 men and 15 women.

*Level: Applied
*

*(p. 381-382)*Read the following research report and answer the question that follow.

A researcher compares mens and womens attitudes toward dating their best friends former girl/boy friend. Specifically, college students are asked to read a story describing a situation in which their best friend breaks up with a partner and they later have an opportunity to date their best friends former partner. Men and women rate the likelihood they would choose to date their best friends former partner using a 10-point scale (0 =*not at all likely*and 9 =*completely likely*). In addition, participants rate the extent to which a similar situation has occurred to them using a 10-point scale (0 =*not at all*and 9 =*completely*). The mean ratings for each question for the two groups, men and women, are presented below:What do the

*p*values associated with each*t*-test tell you besides whether the result is statistically significant?

The smaller the *p* value the greater the probability that an exact replication of this experiment will produce a statistically significant finding at *p* < .05. Therefore, its more likely that the finding for the question regarding the likelihood of dating would be replicated than the similarity-of-situation question.

*Level: Applied
*

*(p. 383)*Read the following research report and answer the question that follow.

A researcher compares mens and womens attitudes toward dating their best friends former girl/boy friend. Specifically, college students are asked to read a story describing a situation in which their best friend breaks up with a partner and they later have an opportunity to date their best friends former partner. Men and women rate the likelihood they would choose to date their best friends former partner using a 10-point scale (0 =*not at all likely*and 9 =*completely likely*). In addition, participants rate the extent to which a similar situation has occurred to them using a 10-point scale (0 =*not at all*and 9 =*completely*). The mean ratings for each question for the two groups, men and women, are presented below:Describe whether a Type I error and whether a Type II error are possible in this study.

A Type I error is possible if, in fact, the null hypothesis of no difference between men and women for the likelihood of dating question is true (in the population of men and women), and therefore, should not have been rejected. The probability of this Type I error is the level of significance, or alpha (*p* = .05). A Type II error occurs when a false null hypothesis is not rejected. This is possible if there truly is a difference for mens and womens experience of a similar situation (in the population), but the results for this sample did not indicate this difference. The experiment or statistical test may not have been sensitive or powerful enough to detect this difference.

*Level: Applied
*

*(p. 387, 355)*Read the following research report and answer the question that follow.

A researcher compares mens and womens attitudes toward dating their best friends former girl/boy friend. Specifically, college students are asked to read a story describing a situation in which their best friend breaks up with a partner and they later have an opportunity to date their best friends former partner. Men and women rate the likelihood they would choose to date their best friends former partner using a 10-point scale (0 =*not at all likely*and 9 =*completely likely*). In addition, participants rate the extent to which a similar situation has occurred to them using a 10-point scale (0 =*not at all*and 9 =*completely*). The mean ratings for each question for the two groups, men and women, are presented below:The square root of 28 (the

*df*) is approximately 5.3. What is Cohens*d*for the difference between ratings for men and women for the question regarding the likelihood of dating? According to Cohens criteria, how would you describe this effect?

The formula for computing *d* based on the *t*-statistic is 2*t* *df*. In this example, 2(2.65) = 5.3; therefore, Cohens *d* = 1.0. This may be described as a large effect.

*Level: Applied
*

** Multiple Choice Questions **

*(p. 381)*The null hypothesis is the assumption that the independent variable

did not have an effect.__A.__

B. had an effect.

C. is a relevant variable.

D. is statistically significant.

*Level: Factual
*

*(p. 381)*The level of significance, or alpha, in psychological research is generally set at

A. .01.

.05.__B.__

C. .10.

D. .50.

*Level: Factual
*

*(p. 381)*The probability we use to define a statistically significant outcome is called

A. an effect size.

B. the null hypothesis.

alpha.__C.__

D. a margin of error.

*Level: Factual
*

*(p. 381)*Null hypothesis significance testing uses the laws of probability to estimate the likelihood of an outcome by first assuming that

A. the null hypothesis is false.

B. an effect of an independent variable is present.

C. the population means are different.

only chance factors caused the outcome.__D.__

*Level: Factual
*

*(p. 382-383)*A result that is__not__statistically significant means that

A. the null hypothesis is definitely false and should be rejected.

B. the null hypothesis is definitely true and should be accepted.

C. we should conclude that the independent variable had no effect whatsoever.

without more information, we should be cautious about concluding that the independent variable did not have an effect.__D.__

*Level: Factual
*

*(p. 383)*The probability we use to define a statistically significant outcome is equivalent to

a Type I error.__A.__

B. a Type II error.

C. the null hypothesis.

D. the population mean.

*Level: Factual
*

*(p. 383)*If a researcher were to use a .01 level of significance rather than the .05 level, the probability of a Type I error would

A. not change.

decrease.__B.__

C. increase.

D. not able to tell without more information.

*Level: Conceptual
*

*(p. 383)*If a researcher were to use a .01 level of significance rather than the .05 level, the probability of a Type II error would

A. not change.

B. decrease.

increase.__C.__

D. not able to tell without more information.

*Level: Factual
*

*(p. 383)*A researcher predicted that an independent variable would produce a difference between a treatment and a control group for the dependent variable. The statistical test resulted in a statistically significant difference. This finding

A. proves the null hypothesis is false.

B. supports the null hypothesis.

C. proves the researchers hypothesis.

supports the researchers hypothesis.__D.__

*Level: Applied
*

*(p. 384)*Which of the following factors is__not__likely to be related to the power of a statistical test comparing two means?

whether the__A.__*t-*or*F-*statistic is used

B. sample size

C. level of significance

D. size of the treatment effect

*Level: Factual
*

*(p. 384)*The primary factor that researchers use to control the power of a statistical test is

A. the size of the treatment effect.

B. the level of significance.

the sample size.__C.__

D. choosing a more heterogeneous population.

*Level: Factual
*

*(p. 386)*The most common error associated with null hypothesis testing in psychological research is

A. a Type I error.

a Type II error.__B.__

C. random sampling.

D. too much power.

*Level: Factual
*

*(p. 386)*When researchers have a good estimate of the expected effect size for an independent variable prior to conducting a study, they should

perform a power analysis.__A.__

B. compute an inferential statistics test.

C. draw confidence intervals for their means.

D. all of these

*Level: Factual
*

*(p. 387)*The*t*-test for independent groups is the appropriate inferential test when

A. a margin of error is needed for single random sample from a population.

comparing two means.__B.__

C. comparing more than two means.

D. calculating a correlation between groups.

*Level: Factual
*

*(p. 387)*The degrees of freedom for a*t*-test for independent groups are

A.*N*1.

B. (*n*_{1}+*n*_{2}) 1.

(__C.__*n*_{1}+*n*_{2}) 2.

D. 2(*N*) 1.

*Level: Factual
*

*(p. 387)*The appropriate inferential test when each subject participates in both conditions of an experiment is

A. a between-subjects*t*-test.

B. a margin of error.

C. a*t*-test for independent groups.

a repeated measures__D.__*t*-test*.*

*Level: Factual
*

*(p. 388)*Results that are statistically significant may__not__be of interest to the scientific community because

A. the studys methodology was poor.

B. the results have little external validity.

C. the treatment effect is too small to be of practical value.

any of these reasons__D.__

*Level: Factual
*

*(p. 388)*When a finding in an experiment is statistically significant, the scientific community can be confident that

A. the experiment is free of confoundings.

B. the finding will generalize to settings beyond those studied in the experiment.

the finding has a low probability of occurring if the null hypothesis were true.__C.__

D. all of these

*Level: Conceptual
*

*(p. 388)*A psychologist conducts a study to test a new treatment. The effect of treatment is statistically significant; the effect size is small according to accepted criteria. When considering the practical or clinical significance of the finding, the psychologist is likely to be concerned about

A. the financial cost of implementing the treatment.

B. the external validity of the finding.

C. whether the study is free of confoundings.

all of these__D.__

*Level: Factual
*

*(p. 389-390)*When deciding how to make a claim about the effect of a variable, researchers should

A. report the results of significance testing instead of measures of effect size.

be aware of limitations association with null hypotheses significance testing.__B.__

C. use the most complicated analysis to tease out the fullest effects.

D. not use confidence intervals.

*Level: Factual
*

*(p. 391)*A researcher plans to conduct a study to compare two groups. Based on previous research, she anticipates a medium effect size. She does a power analysis with alpha level of .05. This power analysis tells her

A. the*t*-test outcome and degrees of freedom she should expect.

B. Cohens*d*for her study.

the sample size she will need to observe a statistically significant finding.__C.__

D. the practical significance of her research.

*Level: Applied
*

*(p. 391)*A researcher tested a treatment and a control group in an experiment with 15 subjects in each group. Although a*t-*test indicated the means for the dependent variable were not statistically different, the effect size for the independent variable was .50. A power analysis revealed that the power of the study was .26. This mea

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