Internal and External Validity and Experimental Research Designs

Question 1

When an investigator conducts a research study, he or she ordinarily not only wants to find out if there is a ____ ____ ____ and ____ ____ but also wants to determine if that relationship is ____ to ____ ____ and ____.

Answer 1

Relationship Between Independent and Dependent Variables; Generalizable to Other People and Circumstances

Question 2

The basic research questions that an investigator wants to answer can be expanded to include a third question:

Answer 2

Is there a relationship between the independent and dependent variables? If so, is the relationship a causal one? Can the relationship between the independent and dependent variables be generalized to other people, settings, times, and operations?

Question 3

A research study is said to have ____ ____ to the extent that it provides accurate answers to the first two research questions and to have ____ ____ to the degree that it produces an accurate answer to the third question. The specific research designs are susceptible, to varying degrees, to factors that can ____ a study’s internal and external validity. Potential threats to internal and external validity are described in this section.

Answer 3

Internal Validity; External Validity; Limit

Question 4

A study has ____ ____ when it allows an investigator to determine if there is a causal relationship between independent and dependent variables Internal validity is threatened whenever an investigator cannot control the three sources of variability described in the previous section.

Answer 4

Internal Validity

Question 5

If an investigator cannot ____ the ____ of the ____ ____, ____ the ____ of any ____ ____, and/or ____ the ____ of ____ ____, he or she cannot be certain whether ____ ____ (or lack of variability) in the dependent variable is attributable to the independent variable or to some other factors Campbell and Stanley have identified eight “generic” extraneous variables that can threaten a study’s internal validity.

Answer 5

Maximize the Effects of the Independent Variable, Control the Effects of any Extraneous Variables, and/or Minimize the Effects of Random Error; Observed Variability

Question 6

____ refers to any biological or psychological change that occurs within subjects during the course of a study as a function of time, is not relevant to the research hypothesis, and affects the status of most or all subjects on the dependent variable in a systematic way. Fatigue, boredom, hunger, and physical and cognitive development are potential ____ ____ that can limit a study’s ____ ____.

Answer 6

Maturation; Maturation Effects; Internal Validity

Question 7

____ would threaten Study #1 if the psychologist assesses the effects of the self-control procedure by comparing the academic achievement test scores of a single group of children with ADHD before and after they are trained in the procedure and there is a five-month interval between testings. In this situation, any improvement in test scores might be due to learning that would have occurred without training in the self-control procedure or to a natural decrease in symptoms rather than to the effects of the procedure.

Answer 7

Maturation

Question 8

The best way to control maturation is to include ____ than ____ ____ in the ____ and ____ ____ ____ to ____. Since subjects in all groups should be ____ to the ____ ____ ____, any observed differences between them on the DV at the end of the study can be ____ to the _ rather than to ____.

Answer 8

More than One Group in the Study and Randomly Assign Subjects to Groups; Susceptible to the Same Maturational Effects; Attributed to the IV; Maturation

Question 9

____ threatens a study’s internal validity when an external event systematically affects the status of subjects on the dependent variable. Historical events are most likely to be a problem when a study includes only ____ ____ and the event occurs at the ____ ____ the ____ ____ is ____. In this situation, any difference in dependent variable performance before and after the intervention is applied might be due to ____ rather than to the _.

Answer 9

History; One Group; Same Time; Independent Variable is Applied; History; IV

Question 10

In Study #2, if the psychologist uses a single-group pretest-posttest design to assess the effects of a moderate dose of a phenothiazine, any observed effect might be due to the drug or to other changes that occurred at about the same time the drug was administered (e.g., a change in hospital staff or policy). History is controlled by including ____ than ____ ____ in the study and ____ ____ ____ to ____. This procedure helps ensure that subjects in all groups are ____ ____ in terms of ____ to ____ ____ so that the investigator is better able to conclude that an observed difference between groups is actually due to the _.

Answer 10

More than One Group; Randomly Assigning Subjects to groups; About Equal; Exposure to External Events; IV

Question 11

____ threatens a study’s internal validity whenever exposure to a test alters subjects’ performance on retesting (e.g., when taking a pretest affects subjects’ scores on the posttest). This threat can be controlled by administering the DV measure only ____ as a ____, by designing the measure in a way that ____ ____ and ____ ____, or by including at least ____ ____ in the study with all groups completing the ____ and ____ so that any difference between groups on the posttest cannot be attributed to the effects of the ____.

Answer 11

Testing; Once; Posttest; Minimizes Memory and Practice Effects; Two Groups; Pre- and Posttests; Postests

Question 12

____: Changes in the ____ or ____ of measuring devices or procedures during the course of a study can confound the study’s results. For instance, if a rater’s ____ ____ over ____, any change in subjects’ pretest and posttest performance might be due to the ____ ____ ____ rather than to the effects of the _.

Answer 12

Instrumentation; Accuracy or Sensitivity; Accuracy Improves over Time; Rater’s Increased Accuracy; IV

Question 13

____ is controlled by including more than ____ ____ in the study and ensuring that all groups are subject to the ____ ____ ____, by using the ____ ____ ____ and ____ with all ____, and by making sure that measuring devices and procedures ____ ____ ____ during the course of the study.

Answer 13

Instrumentation; One Group; Same Instrumentation Effects; Same Measuring Devices and Procedures with all Subjects; Do Not Change

Question 14

____ ____: The tendency of extreme scores on a measure to “regress” (move) toward the mean when the measure is readministered to the same group of people is called ____ ____.

Answer 14

Statistical Regression; Statistical Regression

Question 15

Statistical regression threatens a study’s internal validity whenever subjects have been selected because of their ____ ____ on the _ or a measure that ____ with the _. This threat is avoided by not including ____ ____ ____ in the study or by including ____ than ____ ____ and ensuring that all groups consist of subjects who are ____ ____.

Answer 15

Extreme Status; DV; Correlates; DV; Only Extreme Scores; More than One Group; Similarly Extreme

Question 16

____ is a threat to a study’s internal validity whenever the method used to assign subjects to treatment groups results in systematic differences between the groups at the beginning of the study. Selection is often a problem when ____ ____ are used. It is controlled by ____ ____ ____ to ____ or, when random assignment is not possible, by administering a ____ to subjects to determine if the groups ____ ____ regarding the _.

Answer 16

Selection; Intact Groups; Randomly Assigning Subjects to Groups; Pretest; Differ Initially; DV

Question 17

____ (____) poses a threat to a study’s internal validity when subjects who drop out of one group differ in an important way from subjects who drop out of other groups. Attrition is ____ to control, but ____ can help determine if dropouts and non-dropouts ____ with regard to their ____ ____ on the _.

Answer 17

Attrition (Mortality); Difficult; Pretesting; Differ; Initial Status; DV

Question 18

____ with ____: When groups are initially nonequivalent, ____ can act alone and/or can interact with other factors to threaten a study’s internal validity. There would be an ____ between ____ and ____, for example, when one group of subjects is unintentionally exposed to an external event that does not affect subjects in other groups and the exposure affects their scores or status on the DV.

Answer 18

Interactions with Selection; Selection; Interaction; Selectin and History

Question 19

____ comes from “out there” and occurs at around the same time that the IV is administered, while ____ reflects changes that occur within subjects as the result of the passage of time. ____ is actually an assignment problem.

Answer 19

History; Maturation; Selection

Question 20

When a study has adequate internal validity, the investigator can conclude that observed variations in the (1) ____ variable were caused by variations in the (2) ____ variable rather than by other factors. Campbell and Stanley identified several “generic” extraneous variables that can limit a study’s internal validity.

Answer 20

(1) dependent; (2) independent

Question 21

(3) ____ refers to an external event that is irrelevant to the research hypothesis but that occurs during the course of a study and affects subjects’ status on the (4) ____ variable. (5) ____ refers to changes that occur within subjects during the course Of a study as the result of the passage of time and that have a systematic effect on the DV.

Answer 21

(3) History; (4) dependent; (5) Maturation

Question 22

Statistical (6) ____ is the tendency for very high and very low scores to move toward the mean on retesting. It threatens a study’s internal validity whenever subjects are selected to participate in the study because of their extreme scores on the (7) ____ variable measure. (8) ____ is a problem when subjects in different treatment groups are not similar in terms of important characteristics at the beginning of the study.

Answer 22

(6) regression; (7) dependent; (8) Selection

Question 23

(9) ____ limits a study’s internal validity when subjects who drop out of one group differ in an important way from those who drop out of another group. Finally, (10) ____ can interact with history and threaten a study’s internal validity if one group of subjects is exposed to an external condition that does not affect subjects in other groups.

Answer 23

(9) Attrition; (10) selection

Question 24

A research study has ____ ____ when its results can be generalized to other people, settings, and conditions. When discussing external validity, some authors distinguish between “____ ____” and “____ ____”: The former is used to describe the generalizability of research results to other people, while the latter refers to the generalizability of results to other settings. Ecological validity is a particular problem in ____ ____, which examine the relationship between independent and dependent variables in a laboratory or other non-naturalistic setting.

Answer 24

External Validity; Population Validity; Ecological Validity; Analogue Studies

Question 25

A study’s external validity is always ____ by its ____ ____: If you can’t conclude that there’s a ____ ____ between ____ within the context of the study, you certainly can’t conclude that there’s a relationship for ____ ____ or ____ ____. However, a high degree of internal validity does not guarantee ____ ____. A relationship between variables might exist for the conditions in which the study was conducted or the particular people who participated in the study, but it cannot be ____ to other ____ or to ____ ____.

Answer 25

Limited; Internal Validity; Causal Relationship; Variables; Other People or Other Circumstances; External Validity; Generalized; Conditions; Other People

Question 26

____ ____ ____ and ____: The administration of a pretest can “____” subjects to the purpose of the research study and thereby alter their ____ to the independent variable. When a study’s results have been contaminated by ____ ____, they cannot be generalized to people who have not been pretested.

Answer 26

Interaction Between Testing and Treatment; Sensitize; Reaction; Pretest Sensitization

Question 27

Pretest sensitization is controlled by ____ ____ a ____ or by using the ____ ____-____ ____, which allows an investigator to measure the impact of pretesting on both the external and internal validity of a research study. When using this design, the pretest is treated as an ____ ____ ____ so that its effects on the dependent variable can be ____.

Answer 27

Not Administering a Pretest; Solomon Four-Group Design; Additional Independent Variable; Identified

Question 28

____ ____ ____ and ____: Subjects included in a research study can have ____ that make them ____ to the independent variable in a ____ ____. When this occurs, the results of the study cannot be ____ to people who don’t have those ____.

Answer 28

Interaction Between Selection and Treatment; Characteristics; Respond; Particular Way; Generalized; Characteristics

Question 29

An interaction between ____ and ____ is often a problem when subjects are ____ because volunteers tend to be more ____ than ____-____ and, consequently, might be more ____ to the _. In this situation, the study’s results apply to ____ but can’t be ____ to ____ ____. The best way to eliminate this threat is to ensure that the sample is ____ of the ____ of ____.

Answer 29

Selection and Treatment; Volunteers; Motivated; Non-Volunteers; Responsive; IV; Volunteers; Generalized to Other people; Representative of the Population of Interest

Question 30

____ (____ ____): Research participants may respond to an independent variable in a particular way simply because they know their behavior is being Observed, and this is known as ____. When a study has been contaminated by reactivity, its results cannot be ____ to conditions in which ____ is not ____.

Answer 30

Reactivity (Reactive Arrangements); Reactivity; Generalized; Reactivity is Not Operating

Question 31

Several phenomena are sometimes included in the category of reactivity: The behavior of research subjects can reflect ____ ____, which causes subjects to act in ways they believe will help them avoid negative evaluations. The behavior of subjects can also be altered by ____ ____, which are cues in the experimental setting that inform subjects of the purpose of the study or suggest what behaviors are expected of them.

Answer 31

Evaluation Apprehension; Demand Characteristics

Question 32

A study’s results can be biased by ____ ____ when the experimenter unintentionally provides subjects with cues (demand characteristics) that let them know what behavior is expected or when the experimenter acts in ways that do not affect subjects directly but bias the results of the study.

Answer 32

Experimenter Expectancy

Question 33

There is evidence that an experimenter’s ____ ____ are likely to support the research hypothesis and that experimenters are more likely to recheck their calculations when they conflict with the research hypothesis than when they support it. (Note that some experts consider reactivity and related phenomena to act as direct threats to both ____ and ____ validity.)

Answer 33

Computational Errors; Internal and External

Question 34

Reactivity can be controlled by using ____, ____ (nonreactive) ____, or a ____- or ____-____ ____. When using a ____-____ ____, subjects do not know which treatment group they have been assigned to; in a ____-____ ____, neither the subjects nor the experimenter know which group subjects have been assigned to.

Answer 34

Deception, Unobtrusive Measures, or a Single- or Double-Blind Technique; Single-Blind Technique; Double-Blind Study

Question 35

____ ____ ____ (____ ____, ____ ____): When a study involves exposing each subject to two or more levels of an independent variable (i.e., when the study utilizes a within-subjects design), the effects of one level of the independent variable can be affected by ____ ____ to ____ ____. When this occurs, the results of the study cannot be ____ to situations in which people will be exposed to ____ ____ ____ of the _.

Answer 35

Multiple Treatment Interference (Order Effects, Carryover Effects); Previous Exposure to Another Level; Generalized; Only One Level; IV

Question 36

____ ____ ____ can be controlled by using a ____ ____ in which different subjects (or groups of subjects) receive the levels of the IV in a different order.

Answer 36

Multiple Treatment Interference; Counterbalanced Design

Question 37

The researcher in Study #2 would be using ____ if her study includes three groups and subjects in group #1 receive a low dose of the phenothiazine first, a moderate dose second, and a high dose third; subjects in group #2 receive a moderate dose first, a high dose second, and a low dose third; and subjects in group #3 receive a high dose first, a moderate dose second, and a low dose third. In this situation, if the high dose produces the most favorable results in all three groups, those results could not be attributed to ____ ____ ____.

Answer 37

Counterbalancing; Multiple Treatment Interference

Question 38

Note that the ____ ____ ____ is one type of counterbalanced design and involves administering each level of the IV so that it appears the same number of times in each position (1st, 2nd, 3rd, etc.).

Answer 38

Latin Square Design

Question 39

External validity refers to the (1) ____ of research results to other people, settings, and conditions. (2) ____ is a threat to external validity when administration of a pretest affects how subjects react to the treatment. The effects of pretesting on both internal and external validity can be evaluated by using the (3) ____ four-group design.

Answer 39

(1) generalizability; (2) Pretest sensitization; (3) Solomon

Question 40

Another potential threat is an interaction between (4) ____ and treatment, which occurs when people in the sample differ from people in the (5) ____ in terms of some characteristic that makes them respond differently to the independent variable. (6) ____ is another potential threat to external validity and occurs when research participants act differently because they know their behavior is being observed.

Answer 40

(4) selection; (5) population; (6) Reactivity

Question 41

A subject’s behavior might be altered by (7) ____ which are cues in the research setting that communicate to subjects what behaviors are expected of them. Multiple treatment (8) ____ threatens a study’s external validity when more than one (9) ____ of the IV is administered to each subject. This threat can be controlled by using a Latin square design or other type of (10) ____ design.

Answer 41

(7) demand characteristics; (8) interference; (9) level; (10) counterbalanced

Question 42

The specific research designs available to investigators can be divided into two basic types — ____ ____ and ____-____ ____.

Answer 42

Group Designs and Single-Subject Designs

Question 43

Group (multi-subject) designs include one or more groups of subjects and are classified as either ____-____, ____-____, or ____.

Answer 43

Between-Groups, Within-Subjects, or Mixed

Question 44

When a ____-____ ____ is used, the effects of different levels of an independent variable are assessed by administering each level to a different group of subjects and comparing the status or performance of the groups on the dependent variable.

Answer 44

Between-Groups Design

Question 45

The simplest between-groups designs include ____ ____ ____ with ____ ____. When using this design, the study includes ____ ____ that ____ a ____ ____ of the _. This simple two-group design can be expanded by including ____ than ____ ____ of a ____ ____ ____ or by including ____ or ____ ____ ____.

Answer 45

One Independent Variable with Two Levels; Two Groups that Receive a Different Level of the IV; More than Two Levels; Single Independent Variable; Two or More Independent Variables

Question 46

Whenever a study includes two or more independent variables, it is called a factorial design. The major advantage of a ____ ____ is that it provides more thorough information about the ____ ____ ____ by allowing an investigator to analyze the ____ ____ of each ____ ____ as well as the ____ ____ ____ ____.

Answer 46

Factorial Design; Relationships Among Variables; Main Effects; Independent Variable; Interaction between Independent Variables

Question 47

If the psychologist in Study #1 (self-control procedure) included initial symptom severity (mild, moderate, and severe) as a second independent variable, he would be able to determine if there are ____ ____ of the self-control procedure, main effects of initial symptom severity, and/or an ____ between self-control procedure and initial symptom severity.

Answer 47

Main Effects; Interaction

Question 48

A ____ ____ is the effect of one independent variable on the dependent variable, disregarding the effects of all other independents

Answer 48

Main Effect

Question 49

An ____ refers to the effects of two or more independent variables considered together and occurs when the effects of an independent variable differ at different levels of another independent variable.

Answer 49

Interaction

Question 50

To illustrate, assume the psychologist in Study #1 obtains a sample of 60 children with ADHD and divides them into three groups on the basis of their initial symptom severity (mild, moderate. or severe). He then randomly assigns subjects in each group to the experimental (self-control procedure) group or control (no procedure) group so that there are 10 children in each of the study’s six groups. Although the data collected by the psychologist would have to be analyzed with an inferential statistical test to determine if there are statistically significant ____ and/or ____ ____, tentative conclusions can be drawn by examining the data.

Answer 50

Main and/or Interaction Effects

Question 51

To determine if there are main effects of each independent variable, it is necessary to calculate the “____ ____” (___) for each level of the ____ ____ ____. As shown below, the marginal means for the self-control procedure are 42 and 34. These means were calculated by adding the means in each column and dividing by 3 (the number of means): (52 + 40 + 34)/3 = 42 and (36 + 30 + 36)/3 = 34. Because the marginal means are different, it is possible to tentatively conclude that there are ____ ____ for the self-control procedure: Overall, the self-control procedure seems to have beneficial effects on academic achievement test scores.

Answer 51

Marginal Mean (MM); Two Independent Variables; Main Effects

Question 52

For initial symptom severity, the marginal means are 44, 35, and 35. These means were calculated by adding the means in each row and dividing by 2 (the number of means): (52 + 36)/2 = 44, (40 + 30)/2 = 35, and (34 + 36)/2 = 35. The marginal means suggest that there are also ____ ____ for initial symptom severity. Although children with moderate and severe symptoms obtained the same mean achievement test score (35), children with mild symptoms obtained a higher mean score (44). (If all three means were identical, there would be ____ ____ ____ of symptom severity.) This indicates that, overall, mild symptoms are associated with the highest achievement test scores.

Answer 52

Main Effects; No Main Effects

Question 53

To determine if there is an interaction, the ____ ____ are ____. If there is an interaction, the effects of the self-control procedure will differ at different levels of symptom severity. As can be seen in the above table, for children with mild symptoms, the self-control procedure had a very positive effect: Children with mild symptoms who were trained in the procedure obtained a mean of 52, while those who received no training obtained a mean of 36. For children with moderate symptoms, the self-control procedure also had positive effects, but the difference between the two groups is somewhat smaller: Children with moderate symptoms who received training obtained a mean of 40, while those who received no training obtained a mean of 30.

Answer 53

Cell Means are Inspected

Question 54

Finally, for children with severe symptoms, the self-control procedure did not have a beneficial effect. Children with severe symptoms obtained a higher achievement test score if they received no training (34 with training versus 36 with no training). These results suggest that there is an ____ between the ____ __ — i.e., the effect of the self-control procedure ____ for ____ ____ of ____ ____ ____. (If the effect of the self-control procedure was the ____ for all ____ of ____ ____, there would be ____ ____.)

Answer 54

Interaction; Two IVs; Differs for Different Levels of Initial Symptom Severity; Same for all Levels of Symptom Severity; No Interaction

Question 55

An inspection of the data obtained in Study #1 suggests that there are main effects for both variables as well as an interaction effect. Note that the presence of the interaction invalidates the conclusion that was drawn on the basis of the main effects alone: Overall, the self-control procedure seems to be beneficial (main effect), but a closer inspection of the data shows that this is true only for children with mild and moderate symptoms (interaction). This illustrates the importance of ____ ____ ____ (or lack of main effects) with ____ whenever there is an ____: An interaction is likely to ____ or ____ the conclusions made based on the ____ ____ ____. Also note that a study can have any ____ of ____ and ____ ____. It is possible to have an interaction, for example, without any ____ ____ (or vice versa).

Answer 55

Interpreting Main Effects with Caution; Interaction; Modify or Invalidate; Main Effects Alone; Combination of Main and Interaction Effects; Main Effects

Question 56

Keep in Mind that there cannot be an interaction unless the study has at least ____ __ and that, when there is an interaction, main effects must be interpreted in light of the ____.

Answer 56

Two IVs; Interaction

Question 57

When using a ____-____ (____ ____) ____, all levels of the independent variable are administered sequentially to all subjects. Consequently, comparisons of different levels of the independent variable are made ____ ____ rather than between groups of subjects. Like between-groups designs, within-subjects designs can include ____ ____ ____ of a ____ ____ ____ or can be expanded to include ____ or ____ ____ of a ____ _ or ____ or ____ __.

Answer 57

Within-Subjects (Repeated Measures) Design; Within Subjects; Only Two Levels; Single Independent Variable; Three or More Levels of a Single IV or Two or More IVs

Question 58

The ____-____ ____-____ ____ is one type of within-subjects design. When using this design, the effects of a treatment are evaluated by measuring the ____ ____ ____ ____ at regular intervals before and after the ____ is ____, which allows subjects to act as their own ____-____ ____.

Answer 58

Single-Group Time-Series Design; Dependent Variable Several Times; Treatment is Applied; No-Treatment Controls

Question 59

A shortcoming of the single-group time-series design is that its internal validity can be ____ by ____ when an external event occurs at about the ____ ____ the ____ ____ is ____ and accounts for any observed difference in ____ and ____ ____. However, while this design does not eliminate maturational effects, it helps ____ them because maturation tends to occur ____ ____ ____ and can usually be detected in the ____ ____ of ____ and ____ ____.

Answer 59

Threatened by History; Same Time the Independent Variable is Applied; Pre- and Posttest Scores; Control; Gradually Over Time; Overall Pattern of Pre- and Posttest Scores

Question 60

In another type of within-subjects design, ____ or ____ ____ of an ____ ____ are ____ ____ to each ____, and the ____ ____ is ____ at the ____ of the ____ and then after ____ ____ has ____ ____.

Answer 60

Two or More Levels of an Independent Variable are Applied Sequentially; Subject; Dependent Variable is Measured; Beginning of the Study; Each Level has Been Applied

Question 61

A problem with this design is that it is susceptible to ____ ____ (multiple treatment interference): If the psychologist in Study #2 finds that the moderate dose of the phenothiazine is more effective than the low dose for improving symptoms, this could be because the moderate dose followed a period of time during which patients received the low dose. As noted in the previous section, ____ can be used to control carryover effects.

Answer 61

Carryover Effects; Counterbalancing

Question 62

____ ____ could be controlled in this study, for example, by dividing the patients into two groups and administering the two levels of the phenothiazine in a different order to each group (i.e., the low dose followed by the moderate dose to patients in Group #1 and the moderate dose followed by the low dose to patients in Group #2). If the moderate dose is more effective for patients in both groups, its effects would not be attributable to carryover effects.

Answer 62

Carryover Effects

Question 63

A disadvantage of the time-series design and other within-subjects designs is that the analysis of the data can be confounded by ____. In other words, subjects’ performance on the posttests is likely to ____ with their ____ on the ____. Autocorrelation can inflate the value of the ____ ____ (e.g., the t or F), thereby resulting in an increased probability of making a ____ ¬_ ____. For this reason, the experts recommend that special statistical techniques be used to analyze data collected in a study using a within-subjects design. (A Type I error is described in the section on inferential statistics.)

Answer 63

Autocorrelation; Correlate; Performance; Pretests; Inferential Statistic; Type I Error

Question 64

As its name suggests, a ____ ____ combines between-groups and within-subjects designs by including at least one between-groups independent variable and one within-subjects independent variable.

Answer 64

Mixed Design

Question 65

Mixed designs are common in research studies that involve measuring the ____ ____ ____ ____ or ____. In this type of study, trials or time is an ____ _ and is a ____-____ ____ because comparisons on the dependent variable will be made within subjects across trials or across time (e.g., immediately following treatment, six weeks following treatment, 12 weeks following treatment).

Answer 65

Dependent Variable Across Trials or Time; Additional IV; Within-Subjects Variable

Question 66

Example: In Study #2, the psychologist decides to compare the effects of four levels of therapy (family therapy, individual therapy, a combination of the two, and no therapy) by assigning patients to one of the levels and measuring the short- and long-term effects of therapy by administering the BPRS at four-month intervals for 24 months after therapy begins. Since the study includes a ____-____ ____ (therapy) and a ____-____ ____ (time), it is utilizing a mixed design.

Answer 66

Between-Groups Variable; Within-Subjects Variable

Question 67

When using a (1) ____ groups research design, the effects of an independent variable are assessed by administering each level of the independent variable to a different (2) ____ of subjects and comparing the performance or status of the groups on the (3) ____ variable.

Answer 67

(1) between-; (2) group; (3) dependent

Question 68

In contrast, when using a (4) ____ subjects (repeated measures) design the effects of an independent variable are assessed by comparing the performance or status of the same group of subjects on the (5) ____ variable after receiving, at different times, each level of the independent variable. In the single-group (6) ____ design, the dependent variable is measured several times before and after the independent variable is applied.

Answer 68

(4) within-; (5) dependent; (6) time-series

Question 69

A research design that includes two or more independent variables is called a (7) ____ design. An advantage of this type of design is that it allows an investigator to assess the main effects of each independent variable as well as any interaction between those variables.

Answer 69

(7) factorial

Question 70

A(n) (8) ____ effect is the effect of one independent variable on the dependent variable, while a(n) (9) ____ is the effect of one independent variable on the dependent variable at different (10) ____ of another independent variable.

Answer 70

(8) main; (9) interaction; (10) levels

Question 71

Two characteristics distinguish the ____-____ ____ from the group designs.

Answer 71

Single-Subject Designs

Question 72

Each single-subject design includes at least ____ ____ (no treatment) ____ and ____ ____ ____. As a result, each subject acts as his/her own ____-____ ____.

Answer 72

One Baseline Phase and One Treatment Phase; No-Treatment Control

Question 73

The dependent variable is measured ____ at ____ ____ throughout the ____ and ____ ____. Repeated measurement of the dependent variable helps control any ____ ____ that might otherwise threaten the study’s ____ ____ by enabling an investigator to detect those effects in the pattern of performance on the DV measure.

Answer 73

Repeatedly at Regular Intervals; Baseline and Treatment Phases; Maturational Effects; Internal Validity

Question 74

While these designs are ordinarily used to investigate the effects of an independent variable on the ____ of ____ ____ or a ____ ____ of ____, they can also be used with ____ of ____. The most commonly used single-subject designs are the _ ____, its extensions (e.g., the __ and ___ ____), and the ____ ____ ____.

Answer 74

Behavior of One Subject or a Small Number of Subjects; Groups of Subjects; AB Design; ABA and ABAB Designs; Multiple Baseline Design

Question 75

The simplest single-subject design is the _ ____, which includes a single baseline (A) phase and a single treatment (B) phase. As in all single-subject designs, the dependent variable is measured at ____ ____ during ____ ____.

Answer 75

AB Design; Regular Intervals; Both Phases

Question 76

____ ____ (__, ___, Etc.): The AB design can be expanded to include more than ____ ____ ____ or more than ____ ____ and more than ____ ____ ____. Because any expansion requires ____ the ____ during the ____ and ____ ____ ____, the extensions of the AB design are called ____ or ____ ____.

Answer 76

Reversal Designs (ABA, ABAB); One Baseline Phase; One Baseline; One Treatment Phase; Withdrawing the Treatment; Second and Subsequent Baseline Phases; Reversal or Withdrawal Designs

Question 77

An advantage of the ____ ____ over the simple AB design is that they provide additional control over potential threats to a study’s internal validity. When an ABAB design Is used, if status on the dependent variable returns to the initial baseline (no treatment) level during the second A phase and then to its previous treatment level during the second B phase, an investigator can be more certain that any observed change in the dependent variable is due to the _ rather than to ____, ____, or other factor.

Answer 77

Reversal Designs; IV; History; Maturation

Question 78

The reversal designs are considered ____ when withdrawal of a treatment during a research study would be ____ (e.g., when the treatment has successfully eliminated a self-injurious behavior). In addition, a reversal design does not provide conclusive information if the effects of an independent variable ____ rather than “____” (return to baseline levels) when it is ____. When this occurs, an investigator can’t be certain whether an observed change in the dependent variable was due to the ____ ____ or ____ ____.

Answer 78

Inappropriate; Unethical; Persist; Reverse; Withdrawn; Independent Variable or Other Factor

Question 79

When a reversal design is inappropriate for ethical or practical reasons, an investigator might use a ____ ____ ____. An advantage of this design is that it does not require ____ a treatment during the course of the study but, instead, involves ____ ____ the ____ to different behaviors of the same subject (____ ____ ____ ____), to the same subject in different settings (____ ____ ____ ____), to the same subject on different tasks (____ ____ ____ ____), or to the same behavior of different subjects (____ ____ ____ ____). Once the treatment has been applied to a “____” (i.e., to a behavior, setting, task, or subject), it is not ____ from that ____ during the ____ of the ____.

Answer 79

Multiple Baseline Design; Withdrawing; Sequentially Applying the Treatment (Multiple Baseline Across Behaviors); (Multiple Baseline Across Settings); (Multiple Baseline Across Tasks); (Multiple Baseline Across Subjects); Baseline; Withdrawn; Baseline Course; Study

Question 80

As can be seen in the above figure, ____ applying an ____ to ____ ____ helps determine if the intervention is actually responsible for any ____ ____ in ____ in those ____: If the behavior changes in a setting only after the intervention has been applied in that setting, the investigator can be more certain that the change is due to the ____ rather than to ____ or ____ ____. To be effective, the setting, behaviors, tasks, or subjects chosen for inclusion in the study must be ____ ____. If they are not, it may not be possible to evaluate the ____ of the _ with this ____.

Answer 80

Sequentially; Intervention to Different Settings; Observed Change in Behavior; Settings; Intervention; History or Other Factors; Relatively Independent; Effects; IV; Design

Question 81

Two distinguishing characteristics of the single-subject designs are that they include at least two phases – a (1) ____ ____ (no treatment) phase and a (2) ____ phase – and that they involve measuring the (3) ____ variable at regular intervals during each phase of the study.

Answer 81

(1) baseline; (2) treatment; (3) dependent

Question 82

Three commonly used single-subject designs are the AB design, the reversal design, and the multiple baseline design. The AB design includes one (4) ____ (A) phase and one (5) ____ (B) phase. The reversal designs extend the AB design by including, at a minimum, two (6) _____ phases and one (7) ____ phase.

Answer 82

(4) baseline; (5) treatment; (6) baseline; (7) treatment

Question 83

When using a reversal design, if the subject’s performance on the (8) ____ variable follows the predicted pattern (i.e., if it changes in the expected direction after the treatment is applied and withdrawn), a researcher can conclude that changes in the (9) ____ variable are due to the effects of the (10) ____ variable rather than to history, maturation, or other factors.

Answer 83

(8) dependent; (9) dependent; (10) independent

Question 84

When it is not ethical or practical to withdraw an effective treatment during the course of a study, an investigator can use the multiple (11) ____ design, which involves sequentially applying the (12) ____ variable to two or more “baselines” – i.e., either to two or more behavior, settings, tasks, or subjects. An advantage of this design is that, once the IV is applied to a baseline, it is not (13) ____ during the study.

Answer 84

(11) baseline; (12) independent; (13) withdrawn (removed)