Experimental Research and Method of Control

Question 1

____ an ____ into a ____ ____: Once an investigator has identified an issue to study, he or she translates the issue into a testable research question or hypothesis about the relationship between variables.

Answer 1

Developing an Idea into a Testable Hypothesis

Question 2

____ an ____ ____ ____: The investigator chooses an appropriate research strateg and research design.

Answer 2

Choosing an Appropriate Research Design

Question 3

____ a ____: The investigator identifies the target population, determines how the sample will be selected from the population, and then selects the sample.

Answer 3

Selecting a Sample

Question 4

____ the ____: The investigator conducts the study and collects and records the data for later analysis.

Answer 4

Conducting the Study

Question 5

____ the ____ ____: After collecting the data, the investigator analyzes it using appropriate descriptive and inferential statistical techniques.

Answer 5

Analyzing the Obtained Data

Question 6

____ the ____: The investigator prepares a report of the research results.

Answer 6

Reporting the Results

Question 7

An initial step in conducting a research study is identifying and defining all ____ ____. A ____ is any attribute, behavior, event, or other phenomenon that is capable or varying or existing in at least two different states, conditions, or levels. ____ is a ____ in a research study when the study includes male and female subjects. In contrast, when a characteristic is restricted to a single state or condition, it is called a ____. Gender is a constant when ____ ____ ____ are included in a study.

Answer 7

Relevant Variables; Variable; Gender; Variable; Constant; Only Male Subjects

Question 8

In research, a distinction is made between ____ and ____ ____: A variable is an ____ ____ (___) when it is believed to affect or alter status on another variable (the dependent variable). Conversely, a variable is a ____ ____ (___) when status on that variable seems to “depend on” status on another variable (the independent variable).

Answer 8

Independent and Dependent Variables; Independent Variable (IV); Dependent Variable (DV)

Question 9

If a psychologist designs a study to test the hypothesis that cognitive therapy is more effective than psychodynamic psychotherapy for alleviating depressive symptoms, the ____ ____ is therapy and the ____ ____ is depressive symptoms.

Answer 9

Independent Variable; Dependent Variable

Question 10

The independent variable is often referred to as the “____ “ or “____ “ and is symbolized with the letter “_.” In a true ____ ____ (see below), the investigator “manipulates” the IV by determining which levels of the IV to administer and randomly assigning subjects to the different levels. Note that each independent variable must have at least ____ ____ since it is possible to determine the ____ of an ____, ____, or other phenomenon only when there is a ____ of ____.

Answer 10

Treatment or Intervention; X; Experimental Study; Two Levels; Effects of an Intervention; Characteristic; Point of Comparison

Question 11

The dependent variable is considered the ____ of the ____. It is measured by ____ and ____ and is symbolized with the letter “_.” An investigator doesn’t ____ the ___ but, instead, ____ and ____ it.

Answer 11

Outcome of the Treatment; Pretests and Posttests; Y; Manipulate the DV; Observes and Measures

Question 12

One way to help distinguish between independent and dependent variables is to translate the information given about a study into the following question: _________________________________? To demonstrate how this question can be used to identify a study’s independent and dependent variables, the three research examples that are used in this chapter and the Test Construction chapter will now be introduced.

Answer 12

What is the effect of (INDEPENDENT VARIABLE) on (DEPENDENT VARIABLE)?

Question 13

STUDY #I/SELF-CONTROL PROCEDURE FOR CHILDREN WITH ADHD

Answer 13

A psychologist has designed a self-control procedure that incorporates self-monitoring, self-instruction, and self-reinforcement. The psychologist believes that use of the self-control procedure will improve the academic achievement of children who have received a diagnosis Of Attention-Deficit/Hyperactivity Disorder (ADHD). He plans to test this hypothesis by comparing the academic achievement of children with ADHD who have and have not received training in the procedure.

Question 14

The research question for Study # I would be completed in the following way: What are the effects of the SELF-CONTROL PROCEDURE on the ACADEMIC ACHIEVEMENT of children who have received a diagnosis of ADHD? Completion of the question indicates that Study I has one independent variable (____-____ ____) and one dependent variable (____ ____).

Answer 14

Self-Control Procedure; Academic Achievement

Question 15

STUDY #2ÆREATMENTS FOR SCHIZOPHRENIA

Answer 15

A psychologist wants to compare the effects of four therapy approaches (family therapy, individual psychotherapy, a combination of the two, and no therapy) and three levels of a phenothiazine (high dose, moderate dose, and low dose) on the behavioral and cognitive functioning of hospitalized patients who have received a diagnosis of Schizophrenia. Her study will involve randomly assigning hospitalized patients to one of the treatment and, after a period of time, administering the Psychiatric Rating scale (BPRS) and the WAIS-IV to all of the patients.

Question 16

For study #2, the research question is: What are the effects of THERAPY and a PHENOTHIAZINE on the BPRs and WAIS-IV SCORES of hospitalized patients who received A diagnosis of Schizophrenia? This question indicates that Study #2 has ____ independent variables (____ of ____ and ____ ____) and ____ dependent variables (___ and ___-___ ____).

Answer 16

Twp; Type of Therapy and Phenothiazine Dose; Two; BPRS and WATS-TV Scores

Question 17

STUDY #3/CHARACTERISTICS OF SUCCESSFUL SALESPEOPLE

Answer 17

An organizational psychologist has been hired by a computer manufacturing company to identify factors that predict success as a computer salesperson so that, eventually, job selection measures for this position can be developed. The psychologist decides to assess the product knowledge, attitude toward the company, and interpersonal assertiveness of a group of salespeople and determine each salesperson’s dollar amount of sales during a three-month period.

Question 18

For study #3 the research question is: What are the effects of PRODUCT KNOWLEDGE, ATTITUDE TOWARD THE COMPANY, and INTERPERSONAL ASSERTIVENESS on the DOLLAR AMOUNT OF SALES of computer salespeople? Study #3 has ____ independent variables (____ ____, ____ ____ the ____, and ____ ____) and ____ dependent variable (____ ____ of ____).

Answer 18

Three; Product Knowledge, Attitude Toward the Company, and Interpersonal Assertiveness; One; Dollar Amount of Sales

Question 19

You might have noticed that the independent variables in Study #3 differ from those in Studies #1 and #2. In Studies #1 and #2, the independent variables are ____ ____: The psychologist in each study will be able to determine which levels of the IVs will be administered to subjects. In Study #3, the three IVs are ____ ____, or subject characteristics that cannot be ____ by the psychologist. Although the psychologist in Study #3 will be able to determine if there is a relationship between the study’s independent and dependent variables, because of the inability to manipulate the IVs, she will not be able to determine if any observed relationships are ____ in nature.

Answer 19

Manipulated Variables; Organismic Variables; Controlled; Casual

Question 20

____ and ____ ____: Researchers are sometimes interested in identifying the effects of ____ and/or ____ ____ on an observed relationship between an independent variable and a dependent variable. A ____ ____ is responsible for the observed relationship between the variables. In other words, the ____ variable affects the mediator variable which, in turn, affects the ____ variable.

Answer 20

Mediating and Moderating Variables; Mediator and/or Moderator Variables; Mediator Variable; Independent; Dependent

Question 21

If the researcher in Study #1 believes that the beneficial effects of the self-control procedure on the academic achievement of children with ADHD is due to its effects on the children’s self-efficacy beliefs, he is proposing that self-efficacy beliefs are a ____ ____ — the self-control procedure increases self-efficacy beliefs which, in turn, have a positive effect on academic achievement. To test this belief, the researcher will include a measure of self-efficacy in his study and use ____ ____ or other statistical techniques to determine if self-efficacy ____ the relationship between the self-control procedure and academic achievement test scores.

Answer 21

Mediating Variable; Multiple Regression; Mediates

Question 22

A ____ ____ affects the direction or strength of the relationship between independent and dependent variables. In other words, unlike mediator variables which provide a causal explanation for the relationship between variables, moderator variables affect the ____ of the ____.

Answer 22

Moderator Variable; Strength of the Relationship

Question 23

If the researcher in Study #1 believes that the effects of the self-control procedure on academic achievement will be greater for older children than for younger children, he is predicting that ____ is a ____ ____ — i.e., that ____ ____ the impact of the self-control procedure on academic achievement. To determine if this is true, the researcher will include age as an ____ ____ in his study, and the results of the study will confirm his belief if they indicate that the procedure is more effective for increasing the academic achievement test scores of older children than younger children.

Answer 23

Age is a Moderator Variable; Age Moderates; Independent Variable

Question 24

____ ____: Once a study’s variables have been identified, they must be ____ ____ — i.e., they must be defined in terms of the ____ or ____ that will be used to ____ or ____ them. Some variables are measured ____, while others are measured using a ____ or other instrument or by ____ and ____ ____.

Answer 24

Measuring Variables; Operationally Defined; Method or Process; Identify or Measure; Directly; Test; Observing and Recording Behaviors

Question 25

In Study #3, dollar amount of sales would be measured ____, while interpersonal assertiveness could be assessed by administering a measure of interpersonal assertiveness to salespeople or observing salespeople during sales transactions and recording incidents of interpersonal assertiveness.

Answer 25

Directly

Question 26

Whenever ____ is used to measure a behavior, the ____ that will be used to ____ and ____ the ____ must be ____. One method is to obtain a ____ ____ of the ____ as it actually ____, with the record taking the form of a ____ ____ ____ or an ____ and/or ____ ____. ____ ____, which involves organizing data into categories, can then be used to ____ and ____ the ____ contained in the ____ ____.

Answer 26

Observation; Method; Observe; Record the Behavior; Identified; Narrative Record; Behavior; Occurs; Detailed Written Description; Audio and/or Visual Recording; Content Analysis; Summarize and interpret the information; Narrative Record

Question 27

____ ____ can be viewed as a type of content analysis. It is used by psychologists interested in the ____ ____ (“heeded cognitions”) that underlie ____-____ and other ____ ____ and involves asking a subject to “____ ____” while ____ a ____. The subject’s verbalizations are ____, and the protocol (transcribed record) is later ____ in terms of ____ ____ such as intentions, planning, and evaluations.

Answer 27

Protocol Analysis; Cognitive Processes; Problem-Solving; Complex Tasks; Think Aloud; Solving a Problem; Recorded; Coded; Relevant Categories

Question 28

An alternative to obtaining a complete record of a behavior is to look at ____ ____ of it by employing a systematic method for ____ and ____ the ____ or ____ of the ____ and/or rating the behavior in terms of its ____ ____. Methods of ____ ____ include interval recording and event sampling.

Answer 28

Specific Aspects; Sampling and Recording the Frequency or Duration of the Behavior; Qualitative Characteristics; Behavioral Sampling

Question 29

____ ____ is also known as interval sampling and time sampling and involves observing a behavior for a period of time that has been divided into equal intervals (e.g., a 30-minute period that has been divided into 15-second intervals) and recording whether or not the behavior occurs during each interval. Interval recording is especially useful for studying ____ ____ and behaviors that have no clear ____ or ____ such as laughing, talking, or playing.

Answer 29

Interval Recording; Complex Interactions; Beginning or End

Question 30

____ ____ is also known as event recording and entails observing and recording the behavior each time it occurs. Recording can take several forms including using a ____-____ ____ or recording the times when the behavior ____ and ____. Event sampling is useful for studying behaviors that occur ____, have a ____ ____, or leave a ____ ____ or other product (e.g., a completed worksheet or test).

Answer 30

Event Sampling; Pre-Coded Checklist; Began and Ended; Infrequently; Long Duration; Permanent Record

Question 31

____ ____ is an alternative to behavioral sampling and is used when a goal Of the study is to observe a behavior in a number of settings. It helps increase the ____ of a study’s findings. Finally, ____ ____ entails coding behavioral sequences rather than isolated behavioral events and is used to identify patterns in complex social behaviors — e.g., patterns in interactions between partners or between a child and parent.

Answer 31

Situational Sampling; Generalizability; Sequential Analysis

Question 32

Research can be categorized as (1) ____ or quantitative, and quantitative research is further categorized as nonexperimental or experimental. Nonexperimental research is conducted to collect data on variables, while experimental research is conducted to test (2) ____ about the relationships between variables.

Answer 32

(1) qualitative; (2) hypotheses

Question 33

Variables are behaviors or other characteristics that (3) ____ from person to person or situation to situation. Researchers distinguish between several types of variables: A person’s status on the (4) ____ variable is assumed to affect his/her status on the (5) ____ variable.

Answer 33

(3) vary; (4) independent; (5) dependent

Question 34

For example, if a psychologist conducts a study to test the hypothesis that children who watch violent films are more aggressive than children who watch a nonviolent film, the study’s independent variable is (6) ____ and its dependent variable is (7) ____. To assess the effects of an independent variable on a dependent variable, the independent variable must have at least two (8) ____.

Answer 34

(6) type of film (violent vs. nonviolent); (7) aggressiveness; (8) levels

Question 35

An important decision when using observation to identify or measure a behavior is how to record the behavior. One way is to obtain a narrative record of the behavior. For example, (11) ____ analysis involves recording a subject’s verbalizations when she has been instructed to “think aloud” while solving a complex cognitive problem.

Answer 35

(11) protocol

Question 36

Alternatively, a specific aspect of a behavior can be recorded. (12) ____ recording is particularly useful when the target behavior has no clear beginning or end, while (13) ____ sampling is a useful technique when the behavior occurs infrequently or leaves a permanent record.

Answer 36

(12) Interval; (13) event

Question 37

____ ____ is classified as true experimental or quasi-experimental. All experimental research is characterized by some degree of ____ ____, or ability to control experimental ____ and ____.

Answer 37

Experimental Research; Experimental Control; Conditions and Variables

Question 38

Only ____ ____ ____ provides the amount of control necessary to conclude that observed variability in a dependent variable is caused by variability in an independent variable. This is because, when conducting a true experimental study, an investigator is not only able to control the experimental conditions and determine which levels of the independent variable to include in the study, but, most important, is able to ____ ____ ____ to different ____ ____ (i.e., to different levels of the IV).

Answer 38

True Experimental Research; Randomly Assign Subjects; Treatment Groups

Question 39

The ____ ____ of subjects to groups, or “randomization,” helps ensure that any observed differences between groups on the dependent variable are actually due to the effects of the ____ ____.

Answer 39

Random Assignment; Independent Variable

Question 40

Example: Study # 1 would be a true experimental study if the psychologist ____ ____ children with ADHD to either the experimental (self-control procedure) group or the control (no treatment) group. Because he randomly assigned children to groups, the psychologist would be better able to conclude that an observed difference between the groups on a measure of academic achievement at the end of the study is due to the effects of the self-control procedure rather than to other factors.

Answer 40

Randomly Assigns

Question 41

____-____ ____ also involves investigating the effects of an independent variable on a dependent variable but does not provide an investigator with the same degree of experimental control. Most important, in quasi-experimental research, the investigator cannot ____ the ____ of ____ to ____ ____ but, instead, must use ____ (pre-existing) ____ or a ____ ____.

Answer 41

Quasi-Experimental Research; Control the Assignment of Subjects to Treatment Groups; Intact Groups or a Single Group

Question 42

An early step in planning a research study is to specify the ____ of ____ and the ____ that will be used to ____ a ____ from that ____. To maximize the generalizability of a study’s results, the sample must be ____ of the ____ from which it was drawn in terms of ____ ____ to the ____ ____.

Answer 42

Population of Interest; Method; Select a Sample; Population; Representative; Population; Characteristics Relevant to the Research Study

Question 43

____ ____ is usually used in quantitative research to ensure that the sample is representative of the population.

Answer 43

Probability Sampling

Question 44

____ ____ ____: When using this method, every member of the population has an equal chance of being included in the sample, and the selection of one member from the population has no effect on the selection of another member. ____ ____ reduces the probability that a sample will be ____ in some way and this is true especially when the sample size is ____.

Answer 44

Simple Random Sampling; Random Sampling; Biased; Large

Question 45

____ ____ ____: When the population of interest varies in terms of specific “strata” (characteristics) that are relevant to the research hypothesis, an investigator can use ____ ____ ____ to ensure that each stratum is represented in the sample. This involves dividing the population into the appropriate ____ and randomly selecting subjects from each ____. ____ ____ include gender, age, education level, SES, and racial, ethnic, or cultural background.

Answer 45

Stratified Random Sampling; Stratified Random Sampling; Strata; Stratum; Typical Strata

Question 46

____ ____ entails using simple or stratified random sampling to select units (clusters) of individuals rather than individuals and either including all individuals in the selected units in the research study or randomly selecting individuals from each unit (the latter technique is called ____ ____ ____).

Answer 46

Cluster Sampling; Multistage Cluster Sampling

Question 47

Rather than randomly selecting patients with Schizophrenia from all mental health in-patient programs in the United States, the psychologist in Study #2 could first randomly select 10 in-patient programs and then include all patients or a random sample of patients from each program in her study. Cluster sampling is useful when it is not possible to ____ or ____ ____ to the ____ ____ of ____.

Answer 47

Identify or Obtain Access to the Entire Population of Interest

Question 48

____ ____ refers to the way subjects are selected from the population and enables the investigator to generalize their findings from the sample to the population. ____ ____ refers to the way in which subjects are assigned to different levels of the IV and allows an investigator to be more certain that an observed effect on the DV was actually caused by the IV. ____ ____ that distinguishes true experimental research om quasi-experimental research.

Answer 48

Random Selection; Random Assignment; Random Assignment

Question 49

Experimental research is categorized as true experimental or quasi-experimental. The primary feature that distinguishes true experimental research from quasi-experimental research is that, in the former, the experimenter can (1) ____ subjects to different treatment groups. This allows the experimenter to be more certain that subjects in different groups are initially similar and, consequently, that any observed differences between them on the (2) ____ variable(s) were caused by the (3) ____ variable(s).

Answer 49

(l) randomly assign; (2) dependent; (3) independent

Question 50

Researchers do not ordinarily have access to the entire population of interest and must draw (4) ____ from that population. So that any observed relationship between variables in the sample can be generalized to the (5) ____, the people in the sample must be as (6) ____ of the population as possible in terms of relevant characteristics such as age, gender, and severity of symptoms.

Answer 50

(4) sample; (5) population; (6) representative

Question 51

The simplest way to achieve this goal is to draw a(n) (7) ____ sample, in which every member of the population has an equal chance of being selected for inclusion in the sample. In contrast to other sampling techniques, (8) ____ sampling involves selecting units (groups) of individuals rather than individuals from the population.

Answer 51

(7) simple random; (8) cluster

Question 52

When conducting experimental research, an investigator is usually attempting to answer two basic questions:

Answer 52

Is there a relationship between the independent and dependent variables? Also, is the relationship a causal one?

Question 53

The ability of a study to provide accurate answers to these questions depends on the extent to which the study’s design allows the investigator to ____ the three factors that can cause ____ in the study’s ____ ____.

Answer 53

Control; Variability; Dependent Variable

Question 54

The ____ ____ (experimental variance)

Answer 54

Independent Variable

Question 55

____ ____ (error due to extraneous variables)

Answer 55

Systematic Error

Question 56

____ ____ (error due to random fluctuations in subjects, experimental conditions, methods of measurement, etc.)

Answer 56

Random Error

Question 57

An investigator wants to choose a research design that (a) ____ ____ in the ____ ____ that is due to the ____ ____, (b) ____ ____ that is due to ____ ____, and (c) ____ ____ caused by ____ ____. By doing so, the investigator can be more certain that observed variability in the dependent variable is ____ to the ____ variable rather than to ____.

Answer 57

Maximizes Variability in the Dependent Variable; Independent Variable; Controls Variability Extraneous Variables; Minimizes Variability; Random Error; Attributable to the Independent Variable; Error

Question 58

Although quasi-experimental research provides some control over the three sources of variability, an investigator’s control is maximized when he or she conducts a ____ ____ ____.

Answer 58

True Experimental Study

Question 59

True experimental research enhances a researcher’s ability to ____ ____ due to the ____ (experimental) ____ by allowing him or her to make the levels of the independent variable as ____ as ____ so that its effects on the dependent variable can be ____. In Study #1 (self-control procedure), the psychologist could maximize the effects of the IV by ensuring that children in the experimental group receive adequate training in the self-control procedure and that children in the control group are not exposed to any aspect of the procedure.

Answer 59

Maximize Variability; Independent Variable; Different as Possible; Detected

Question 60

An ____ (____) ____ is a source of ____ ____. It is a variable that is ____ to the study’s research hypothesis but ____ the study’s results because it has a ____ ____ on (correlates with) the ____ ____. In Study #1, initial symptom severity would be a potential extraneous variable because symptom severity could be expected to correlate with academic achievement — i.e., children with less severe symptoms are likely to do better on a measure of achievement.

Answer 60

Extraneous (Confounding) Variable; Systematic Error; Irrelevant; Confounds; Systematic Effect; Dependent Variable

Question 61

____ ____ of ____ to ____ ____: An investigator can equalize the effects of all known and unknown extraneous variables by ____ ____ ____ to the ____ ____ of the ____ ____. Random assignment of subjects to groups is considered the most “____” ____ of ____ ____ and is the primary characteristic that sets ____ ____ ____ apart from other types of research.

Answer 61

Random Assignment of Subjects to Treatment Groups; Randomly Assigning Subjects to the Different Levels of the Independent Variable(s); “Powerful” Method of Experimental Control; True Experimental Research

Question 62

____ the ____ ____ ____: An investigator can eliminate the confounding effects of an extraneous variable by selecting subjects who are homogeneous with respect to that variable. The primary shortcoming of this method of control is that it limits the ____ of the research results. If the psychologist in Study #1 included only children with mild symptoms in his study, he would not be able to generalize the study’s results to children with moderate or severe symptoms.

Answer 62

Holding the Extraneous Variable Constant; Generalizability

Question 63

____ ____ on the ____ ____: Another way to ensure that groups are equivalent is to ____ ____ in terms of their status on the ____ ____ and then randomly assign matched subjects to one of the treatment groups. Matching is particularly useful when the sample size is ____ ____ to guarantee that random assignment will ____ ____ with regard to the ____ ____. The psychologist in Study #1 could control initial symptom severity by matching subjects in pairs on the basis of their symptom severity and then randomly assigning one member of each pair to the experimental group and the other member to the control group.

Answer 63

Matching Subjects on the Extraneous Variable; Match Subjects; Extraneous Variable; Too Small; Equalize Groups; Extraneous Variable

Question 64

____ the ____ ____ into the ____ (“____”): An extraneous variable can be controlled by including it in the study as an additional independent variable so that its effects on the dependent variable can be statistically analyzed. When using this technique, subjects are not individually matched but are “____” (____) on the basis of their ____ on the ____ ____, and subjects in each block are then ____ ____ to one of the ____ ____.

Answer 64

Building the Extraneous Variable into the Study (“Blocking”); “Blocked” (Grouped); Status; Extraneous Variable; Randomly Assigned; Treatment Groups

Question 65

The psychologist in Study #1 could block children in terms of their initial level of symptom severity (e.g., mild, moderate, severe) and randomly assign children in each block to either the experimental or control group. In this situation, Study #1 includes two independent variables — treatment and symptom severity. (Note that, when a researcher includes an extraneous variable as an independent variable in a study, the extraneous variable is also known as a ____ ____.)

Answer 65

Moderator Variable

Question 66

____ ____ of the ____ ____: When an investigator has information on each subject’s status or score on an extraneous variable, he or she can use the ____ (analysis of covariance) or other statistical technique to remove ____ in the ____ ____ that is due to the ____ ____.

Answer 66

Statistical Control of the Extraneous Variable; ANCOVA; Variability in the Dependent Variability; Extraneous Variable

Question 67

In essence, the ANCOVA controls an ____ ____ (the “____”) by ____ all ____ with regard to their ____ on that ____. Statistical control is a particularly useful method in quasi-experimental research in which subjects cannot be ____ ____ to ____ ____.

Answer 67

Extraneous Variable; Covariate; Equalizing all Subjects; Status; Variable; Randomly Assigned to Treatment Groups

Question 68

Experimental research (especially true experimental research) helps an investigator ____ the ____ of ____ (unpredictable) ____ in subjects, conditions, and measuring instruments by allowing him or her to ____ ____ ____ and ____.

Answer 68

Minimize the Effects of Random Fluctuations; Control Experimental Conditions and Procedures

Question 69

To minimize the effects of ____ ____, an investigator can make sure that subjects do not become fatigued during the course of the study, that the experimental setting is free from distractions and fluctuations in environmental conditions, and that all measuring devices are reliable.

Answer 69

Random Error

Question 70

An Important goal in choosing a research design is to pick a design that minimizes the effects of both ____ and ____ ____; ____ ___ (error due to extraneous variables).

Answer 70

Systematic and Random Error; Systematic Error

Question 71

When conducting an experimental research study, an investigator wants a design that will maximize variability in the dependent variable that is due to the (1) ____, control variability due to (2) ____, and minimize variability due to (3) ____.

Answer 71

(1) independent variable; (2) extraneous variables (systematic error); (3) random error

Question 72

Experimental variability, or variability in the dependent variable that is due to the (4) ____ variable, is maximized when groups are made as different as possible with respect to that variable, while variability due to (5) ____ error is minimized by ensuring that random fluctuations in subjects, conditions, and measuring instruments are eliminated or equalized among all treatment groups.

Answer 72

(4) independent; (5) random

Question 73

A number of techniques are used to control the effects of extraneous variables, which are irrelevant to the research hypothesis but correlate with the (6) ____ variable. The random (7) ____ of subjects to different levels of the independent variable is considered the most powerful method of control because it helps ensure that groups are

Answer 73

(6) dependent; (7) assignment

Question 74

initially (8) ____ with regard to all known and unknown extraneous variables, Matching is useful for controlling an extraneous variable when the number of subjects is too (9) ____ to guarantee that random assignment will equalize the groups in terms of an extraneous variable.

Answer 74

(8) equivalent; (9) small

Question 75

When using blocking, subjects are not individually matched but are (10) ____ in terms of their status on the extraneous variable, and subjects within each (11) ____ are randomly assigned to one of the treatment groups. Finally, the ANCOVA or other statistical technique can be used to statistically (12) ____ the effects of an extraneous variable on the DV.

Answer 75

(10) blocked (grouped); (11) block (group); (12) remove