Question 1

The group to which a researcher wants the findings to ultimately apply is the

Accepted Answer

The target population is the group to which the researcher wants the findings to ultimately apply. It is the group of individuals or things that the researcher intends to generalize the findings of the study to. The accessible population is the group of individuals or things that the researcher can realistically access and gather data from, while the sample is a subset of the accessible population that is selected for the study. Probability samples are a type of sample in which each member of the accessible population has a known probability of being selected for the study.

Question 2

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below.
-Refer to Exhibit 10-7.The experimental group had a higher learning/growth rate than the control group even before the experiment began.

Accepted Answer

The threat to internal validity illustrated in this example is selection-maturation interaction, as the experimental group may have been naturally predisposed to a higher learning/growth rate even before the experiment began. This makes it difficult to attribute the observed difference in learning/growth rate solely to the experimental treatment.

Question 3

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements.
-Refer to Exhibit 10-6.Last year's math grades are taken into consideration when analyzing the posttest scores following the use of a new math teaching method.

Accepted Answer

ANCOVA (analysis of covariance) is the appropriate choice for controlling for intersubject differences when there is a pre-existing variable (in this case, previous math grades) that is related to the outcome variable (posttest scores). ANCOVA adjusts for these differences by including the pre-existing variable as a covariate in the analysis, allowing for a more accurate comparison of the effects of the new math teaching method.

Question 4

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements.
-Refer to Exhibit 10-6.This procedure eliminates some matching problems but makes generalization harder to do.

Accepted Answer

Homogeneous selection involves selecting subjects that are similar in characteristics relevant to the study, which can reduce some matching problems but may limit the generalizability of the findings to a broader population.

Question 5

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below.
-Refer to Exhibit 10-7.The students who scored extremely high on a test would score lower if given the test again.

Accepted Answer

This is an example of statistical regression, where extreme scores on a test tend to move closer to the mean upon retesting.

Question 6

A pretest may be used in an experiment

Accepted Answer

A pretest can serve multiple purposes in an experiment, including as a matching variable to ensure groups are equivalent, as a measure of change being investigated in the experiment, and as a baseline measure to assess group differences before the intervention is introduced. Therefore, all of the choices are true.

Question 7

A researcher investigating the effect of a new drug administers a placebo to the control group in order to

Accepted Answer

By administering a placebo to the control group, the researcher can separate the psychological aspects of the treatment from other effects, such as the placebo effect or natural recovery. This helps to determine the true efficacy of the new drug. The other options do not accurately describe the purpose of administering a placebo to the control group.

Question 8

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below.
-Refer to Exhibit 10-7.The students scored much higher on the posttest because the posttest was easier than the pretest.

Accepted Answer

Instrumentation threats to internal validity occur when there are inconsistencies in the measurement process, such as changes in the test instrument itself that might affect outcomes. In this case, the posttest being easier than the pretest is a clear example of an instrumentation threat, as the change in the difficulty level of the test could lead to differences in scores that are not attributable to the treatment or intervention being studied.

Question 9

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below.
-Refer to Exhibit 10-7.Some students left the experimental program because of a conflict with sports.

Accepted Answer

Experimental mortality refers to the loss of participants during the course of the study, and in this example, some students left the program due to a conflict with sports, which could impact the internal validity of the study by creating bias in the remaining participant sample. None of the other options (instrumentation, selection-maturation interaction, statistical regression, diffusion) are directly related to the loss of participants.

Question 10

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements.
-Refer to Exhibit 10-6.A teacher flips a coin for each child to determine if the child will be in the control or experimental group.

Accepted Answer

Random assignment involves assigning subjects to either the control or experimental group in a completely random manner, such as flipping a coin. This method helps to ensure that any differences between the two groups are due to chance and not systematic differences between the groups.

Question 11

The term "randomization" refers to

Accepted Answer

Randomization specifically refers to the random assignment of subjects into groups. Random selection is a separate concept related to how individuals are chosen to be part of the sample for a study, and sampling techniques are a broader category of methods used to select a sample from a larger population.

Question 12

A confounding variable is one which

Accepted Answer

A confounding variable is an extraneous variable that has not been properly controlled, and it affects the relationship between the independent and dependent variables, leading to erroneous conclusions. Therefore, option C is the correct choice. Option A is incorrect because a variable that has no relationship with the dependent variable cannot be a confounding variable. Option B is incorrect because if a variable is controlled, it cannot act as a confounding variable. Option D is also incorrect because option A is not always true, and option B is not sufficient to explain the concept of confounding variables.

Question 13

Exhibit 10-8: Choose the term that is described in each of the phrases below.
-Refer to Exhibit 10-8.Removes the part of each subject's posttest score that is in common with his/her pretest score.

Accepted Answer

Analysis of covariance (ANCOVA) is the statistical technique used to remove the part of each subject's posttest score that is in common with his/her pretest score. This is done to increase the sensitivity of the study to detect differences between groups, as preexisting differences between participants can affect the posttest scores.

Question 14

The term "control" in research generally refers to controlling

Accepted Answer

Controlling extraneous variables is crucial in research because they can influence the relationship between the independent variable and the dependent variable. By controlling these variables, researchers can ensure that any observed effects are due to the independent variable manipulation and not other factors. Controlling dependent variable measurement, design selection, and independent variable manipulation are also important aspects of research, but they do not fall under the umbrella of "control."

Question 15

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements.
-Refer to Exhibit 10-6.Only boys of ages 6-8 from an urban community were selected for a study.

Accepted Answer

Homogeneous selection is used in this scenario because only boys of ages 6-8 from an urban community were selected, making the group as similar as possible in terms of age, gender, and living environment.

Question 16

In a study of aggression, the instrument used may not really measure aggression but rather assertiveness.If so, this would most likely affect the ____validity of the study.

Accepted Answer

This would affect the construct validity of the study, as the instrument is not measuring the construct of interest (aggression) accurately. Construct validity refers to the degree to which a measure actually measures what it claims to measure.

Question 17

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements.
-Refer to Exhibit 10-6.Each subject in the control group has a corresponding subject in the experimental group who has the same IQ score within three points.

Accepted Answer

Randomized matching is a method used to minimize differences between groups before the treatment. In this case, each subject in the control group has a corresponding subject in the experimental group who has the same IQ score within three points, which is achieved through randomized matching. ANCOVA and homogeneous selection are not relevant in this case. Random assignment refers to randomly assigning subjects to either the control or the experimental group, which is not applicable here. Using subjects as their own controls is a different type of control, where each subject acts as their own control group, which is also not applicable here.

Question 18

Generalization from the accessible population to the target population is assessed

Accepted Answer

Generalization from the accessible population to the target population is often assessed judgmentally, as it involves making informed decisions about how well the sample and findings can be expected to represent the broader population. Statistical methods may support this process, but the final assessment often involves expert judgment considering the context, sample characteristics, and study design.

Question 19

An experiment conducted in a highly controlled lab setting is more likely to have problems with ____ than is an experiment conducted in a classroom setting.

Accepted Answer

Experiments conducted in highly controlled lab settings often face challenges with external validity, which refers to the extent to which the results of a study can be generalized to other situations and to other people. The artificial nature of such settings may limit the applicability of the findings to real-world scenarios, unlike experiments in more naturalistic settings like classrooms, which might better reflect real-world conditions.

Question 20

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements.
-Refer to Exhibit 10-6.Assigning the same subjects to all experimental conditions and obtaining measurements under all conditions.

Accepted Answer

This approach is described as using subjects as their own controls, where each subject experiences all conditions of the experiment, allowing for direct comparison of outcomes within the same individuals over time or across different conditions. This method effectively controls for intersubject differences by eliminating variability between different subjects, as each subject serves as their own control.

Quiz 10: Experimental Research

The group to which a researcher wants the findings to ultimately apply is the

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below. -Refer to Exhibit 10-7.The experimental group had a higher learning/growth rate than the control group even before the experiment began.

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements. -Refer to Exhibit 10-6.Last year's math grades are taken into consideration when analyzing the posttest scores following the use of a new math teaching method.

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements. -Refer to Exhibit 10-6.This procedure eliminates some matching problems but makes generalization harder to do.

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below. -Refer to Exhibit 10-7.The students who scored extremely high on a test would score lower if given the test again.

A pretest may be used in an experiment

A researcher investigating the effect of a new drug administers a placebo to the control group in order to

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below. -Refer to Exhibit 10-7.The students scored much higher on the posttest because the posttest was easier than the pretest.

Exhibit 10-7: Identify the threats to internal validity illustrated in the example below. -Refer to Exhibit 10-7.Some students left the experimental program because of a conflict with sports.

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements. -Refer to Exhibit 10-6.A teacher flips a coin for each child to determine if the child will be in the control or experimental group.

The term "randomization" refers to

A confounding variable is one which

Exhibit 10-8: Choose the term that is described in each of the phrases below. -Refer to Exhibit 10-8.Removes the part of each subject's posttest score that is in common with his/her pretest score.

The term "control" in research generally refers to controlling

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements. -Refer to Exhibit 10-6.Only boys of ages 6-8 from an urban community were selected for a study.

In a study of aggression, the instrument used may not really measure aggression but rather assertiveness.If so, this would most likely affect the ____validity of the study.

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements. -Refer to Exhibit 10-6.Each subject in the control group has a corresponding subject in the experimental group who has the same IQ score within three points.

Generalization from the accessible population to the target population is assessed

An experiment conducted in a highly controlled lab setting is more likely to have problems with ____ than is an experiment conducted in a classroom setting.

Exhibit 10-6: Choose the intersubject difference control that best corresponds with the following statements. -Refer to Exhibit 10-6.Assigning the same subjects to all experimental conditions and obtaining measurements under all conditions.