Question 1

In an experiment that involves two groups, there is/are _____ source(s) of variability.

Accepted Answer

A)  No 
B)  1 
C)  2 
D)  3 
A)  No 
B)  1 
C)  2 
D)  3

Question 2

In an experiment, the FEWEST number of independent variables that you can have would be

Accepted Answer

A)  zero. 
B)  one. 
C)  two. 
D)  Cannot determine without more information. 
A)  zero. 
B)  one. 
C)  two. 
D)  Cannot determine without more information.

Question 3

Understanding Experiments with Two Groups - Answer Key
Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data was obtained:
 GROUP $1 =$ Received drug
GROUP $2 =$ Received placebo
Variable $=$ Depression level
$\begin{array} { l l l l } \text { GROUP } & N & \text { Mean } & S D \ \text { GROUP 1 } & 10 & 3.21 & 1.035 \ \text { GROUP 2 } & 10 & 5.77 & 1.772 \ t = 5.785 & d f = 9 & p = 0.017 & \text { Cohen's } d = .88 \end{array}$
-What is the dependent variable?

Accepted Answer

The answer of Understanding Experiments with Two Groups - Answer...

Question 4

Questions refer to the following computer output in which a researcher measured anxiety in a sample before therapy and after therapy. Table 10-2
GROUP $1 =$ Before therapy
GROUP 2 = After therapy
Variable $=$ Anxiety scores

$\begin{array}{lllll}
\text { GROUP } & N & \text { Mean } & S D & \text { Standard Error } \
\text { GROUP 1 } & 10 & 11.00 & 3.197 & 1.011 \
\text { GROUP 2 } & 10 & 8.90 & 3.573 & 1.130
\end{array}$

$\text { Mean difference }=2.100 \quad\quad\quad S D=1.287 \quad\quad\quad \text { Std Error }=0.417$

$\begin{array}{lll}
\text { Corr }=0.934 & p=0.000 & \
t=5.161 & d f=9 & p=0.001
\end{array}$
-Consult Table 10-2. How many people are in the sample?

Accepted Answer

A)  9 
B)  10 
C)  20 
D)  100 
A)  9 
B)  10 
C)  20 
D)  100

Question 5

Which of the following is a limitation of the ex post facto design?

Accepted Answer

A)  Participants who are exposed to the DV multiple times can become sensitized to the area under investigation. 
B)  Experimenter bias is a greater problem in ex post facto research compared with other research designs. 
C)  It is difficult to find natural pairs. 
D)  You cannot be certain that the IV is the only difference between groups. 
A)  Participants who are exposed to the DV multiple times can become sensitized to the area under investigation. 
B)  Experimenter bias is a greater problem in ex post facto research compared with other research designs. 
C)  It is difficult to find natural pairs. 
D)  You cannot be certain that the IV is the only difference between groups.

Question 6

Bernice conducts a study on the effects of violent television on children. She obtains a sample of 30 aggressive children and 30 non-aggressive children. She has the aggressive children watch 15 minutes of aggressive television and the non-aggressive children watch 15 minutes of non-aggressive television. This study represents a _________ study.

Accepted Answer

A)  correlational 
B)  confounded 
C)  within-subjects 
D)  All of the above. 
A)  correlational 
B)  confounded 
C)  within-subjects 
D)  All of the above.

Question 7

Random assignment controls ________ extraneous variables.

Accepted Answer

A)  known 
B)  unknown 
C)  correlated-groups 
D)  ex post facto 
A)  known 
B)  unknown 
C)  correlated-groups 
D)  ex post facto

Question 8

Degrees of freedom in the two-correlated groups design are _______, and degrees of freedom in the two-independent groups design are _________.

Accepted Answer

A)  N - 1; N - 1 
B)  N - 2; N - 2 
C)  N - 1; N - 2 
D)  N - 2; N - 1 
A)  N - 1; N - 1 
B)  N - 2; N - 2 
C)  N - 1; N - 2 
D)  N - 2; N - 1

Question 9

Variability in DV scores that is due to the effects of the IV is known as __________ variability.

Accepted Answer

A)  between-groups 
B)  error 
C)  within-subjects 
D)  degrees of freedom 
A)  between-groups 
B)  error 
C)  within-subjects 
D)  degrees of freedom

Question 10

In a two-group design, the group of participants that receives the IV is referred to as the ________ group, and the group of participants that does not receive the IV is referred to as the _________ group.

Accepted Answer

A)  independent; dependent 
B)  dependent; independent 
C)  control; experimental 
D)  experimental; control 
A)  independent; dependent 
B)  dependent; independent 
C)  control; experimental 
D)  experimental; control

Question 11

A research approach in which the experimenter cannot directly manipulate the IV but can only measure an IV because it is predetermined is known as a(n)

Accepted Answer

A)  case study. 
B)  true experiment. 
C)  ex post facto research design. 
D)  participant observation. 
A)  case study. 
B)  true experiment. 
C)  ex post facto research design. 
D)  participant observation.

Question 12

Random assignment works best when

Accepted Answer

A)  there are three or more groups instead of two. 
B)  the researcher can match participants on some predetermined variable. 
C)  there are multiple dependent variables. 
D)  the sample size is large. 
A)  there are three or more groups instead of two. 
B)  the researcher can match participants on some predetermined variable. 
C)  there are multiple dependent variables. 
D)  the sample size is large.

Question 13

Why does using a correlated-groups design reduce error variability?

Accepted Answer

Using a correlated-groups design, also k

Question 14

Variability in DV scores that is due to factors other than the IV is known as _________ variability.

Accepted Answer

A)  degrees of freedom 
B)  between-groups 
C)  error 
D)  within-subjects 
A)  degrees of freedom 
B)  between-groups 
C)  error 
D)  within-subjects

Question 15

A method of assigning research participants to groups so that each participant has an equal chance of being in any group is known as

Accepted Answer

A)  random selection. 
B)  random assignment. 
C)  between-subjects assignment. 
D)  correlated assignment. 
A)  random selection. 
B)  random assignment. 
C)  between-subjects assignment. 
D)  correlated assignment.

Question 16

Questions refer to the following computer output in which a researcher compared the GPA of traditional (aged 18-22) and nontraditional (aged 23 or older) students.
Table 10-1
GROUP $1 =$ Aged $18 - 22$
GROUP $2 =$ Aged 23 or older
Variable $=$ Grade point average

$\begin{array} { l c c c c } \text { GROUP } & N & \text { Mean } & S D & \text { Standard Error } \ \text { GROUP 1 } & 15 & 2.95 & 0.556 & 0.143 \ \text { GROUP 2 } & 15 & 3.08 & 0.524 & 0.135 \end{array}$

$F _ { \max }$ test $\quad F = 0.225 \quad p = 0.639$
Equal Variances Assumed
$t = - 0.68 \quad d f = 28 \quad p = 0.509$
Equal Variances Not Assumed
$t = - 0.68 \quad d f = 27.90 \quad p = 0.509$
-Consult Table 10-1. The statistical analysis is a(n) __________ samples t test.

Accepted Answer

A)  independent 
B)  correlated 
C)  paired 
D)  repeated measures 
A)  independent 
B)  correlated 
C)  paired 
D)  repeated measures

Question 17

What is natural pairs? Identify one disadvantage associated with the use of natural pairs.

Accepted Answer

Natural pairs, in the context of researc

Question 18

Which of the following is NOT associated with a within-subjects comparison?

Accepted Answer

A)  Natural pairs 
B)  Matched pairs 
C)  Repeated measures 
D)  Random assignment 
A)  Natural pairs 
B)  Matched pairs 
C)  Repeated measures 
D)  Random assignment

Question 19

Understanding Experiments with Two Groups - Answer Key
Twenty sets of depressed twins are obtained for a study on the effects of a new antidepressant. In each twin set, one twin is assigned to receive the drug, and the other is designed to receive the placebo. Three months later, depression levels are measured on a scale from 1 (not at all depressed) to 7 (very depressed). The following data was obtained:
 GROUP $1 =$ Received drug
GROUP $2 =$ Received placebo
Variable $=$ Depression level
$\begin{array} { l l l l } \text { GROUP } & N & \text { Mean } & S D \ \text { GROUP 1 } & 10 & 3.21 & 1.035 \ \text { GROUP 2 } & 10 & 5.77 & 1.772 \ t = 5.785 & d f = 9 & p = 0.017 & \text { Cohen's } d = .88 \end{array}$
-Is the effect size small, medium, or large? How do you know?

Accepted Answer

Cohen's d is .88, wh

Question 20

The goal in an experiment is to __________ the between-groups variability and ___________ the error variability.

Accepted Answer

A)  maximize; maximize 
B)  minimize; minimize 
C)  maximize; minimize 
D)  minimize; maximize 
A)  maximize; maximize 
B)  minimize; minimize 
C)  maximize; minimize 
D)  minimize; maximize

In an experiment that involves two groups, there is/are _____ source(s) of variability.

In an experiment, the FEWEST number of independent variables that you can have would be

Which of the following is a limitation of the ex post facto design?

Random assignment controls ________ extraneous variables.

Degrees of freedom in the two-correlated groups design are _, and degrees of freedom in the two-independent groups design are ___.

Variability in DV scores that is due to the effects of the IV is known as __________ variability.

In a two-group design, the group of participants that receives the IV is referred to as the group, and the group of participants that does not receive the IV is referred to as the _ group.

A research approach in which the experimenter cannot directly manipulate the IV but can only measure an IV because it is predetermined is known as a(n)

Random assignment works best when

Why does using a correlated-groups design reduce error variability?

Variability in DV scores that is due to factors other than the IV is known as _________ variability.

A method of assigning research participants to groups so that each participant has an equal chance of being in any group is known as

What is natural pairs? Identify one disadvantage associated with the use of natural pairs.

Which of the following is NOT associated with a within-subjects comparison?

The goal in an experiment is to the between-groups variability and _ the error variability.

Psychological Research and the Research Methods Course

Developing a Good Research Idea and Conducting an Ethical Project

Qualitative Research Methods

Nonexperimental Methods: Descriptive Methods, Correlational Studies, Ex Post Facto Studies, Surveys and Questionnaires, Sampling, and Basic Research Strategies

Using the Scientific Method in Psychology

Conducting a Good Experiment I: Variables and Control

Conducting a Good Experiment Ii: Final Considerations, Unanticipated Influences, and Cross-Cultural Issues

Internal and External Validity

Using Statistics to Answer Questions

Designing, Conducting, Analyzing, and Interpreting Experiments With More Than Two Groups

Designing, Conducting, Analyzing, and Interpreting Experiments With Multiple Independent Variables

Alternative Research Designs

Writing and Assembling an Apa-Format Research Report

Filters

Exam 10: Designing, Conducting, Analyzing, and Interpreting Experiments With Two Groups

In an experiment that involves two groups, there is/are _____ source(s) of variability.

In an experiment, the FEWEST number of independent variables that you can have would be

Which of the following is a limitation of the ex post facto design?

Random assignment controls ________ extraneous variables.

Degrees of freedom in the two-correlated groups design are _______, and degrees of freedom in the two-independent groups design are _________.

Variability in DV scores that is due to the effects of the IV is known as __________ variability.

In a two-group design, the group of participants that receives the IV is referred to as the ________ group, and the group of participants that does not receive the IV is referred to as the _________ group.

A research approach in which the experimenter cannot directly manipulate the IV but can only measure an IV because it is predetermined is known as a(n)

Random assignment works best when

Why does using a correlated-groups design reduce error variability?

Variability in DV scores that is due to factors other than the IV is known as _________ variability.

A method of assigning research participants to groups so that each participant has an equal chance of being in any group is known as

What is natural pairs? Identify one disadvantage associated with the use of natural pairs.

Which of the following is NOT associated with a within-subjects comparison?

The goal in an experiment is to __________ the between-groups variability and ___________ the error variability.

Psychological Research and the Research Methods Course

Developing a Good Research Idea and Conducting an Ethical Project

Qualitative Research Methods

Nonexperimental Methods: Descriptive Methods, Correlational Studies, Ex Post Facto Studies, Surveys and Questionnaires, Sampling, and Basic Research Strategies

Using the Scientific Method in Psychology

Conducting a Good Experiment I: Variables and Control

Conducting a Good Experiment Ii: Final Considerations, Unanticipated Influences, and Cross-Cultural Issues

Internal and External Validity

Using Statistics to Answer Questions

Designing, Conducting, Analyzing, and Interpreting Experiments With More Than Two Groups

Designing, Conducting, Analyzing, and Interpreting Experiments With Multiple Independent Variables

Alternative Research Designs

Writing and Assembling an Apa-Format Research Report

Filters

Degrees of freedom in the two-correlated groups design are _, and degrees of freedom in the two-independent groups design are ___.

In a two-group design, the group of participants that receives the IV is referred to as the group, and the group of participants that does not receive the IV is referred to as the _ group.

The goal in an experiment is to the between-groups variability and _ the error variability.