Experts only. Please use only the methods in the applicable chapters. Show all work and calculations. Books: Jackson, S.L. (2012) Research methods and statistics: A critical thinking approach
Chapter 11 , selected even exercises p 308-310
4. If a researcher decides to use multiple comparisons in a study with three conditions, what is the probability of a Type I error across these comparisons? Use the Bonferroni adjustment to determine the suggested alpha level.
10. In a study of the effects of stress on illness, a researcher tallied the number of colds people contracted during a 6-month period as a function of the amount of stress they reported during that same time period. There were three stress levels: minimal, moderate, and high stress. The sums of squares appear in the following ANOVA summary table. The mean for each condition and the number of subjects per condition are also noted.
Sourcedf SS MS F
Between groups 22.167
Within groups 14.750
Total 36.917
Stress Level Mean N
Minimal 3 4
Moderate 4 4
High 6 4
a. Complete the ANOVA summary table.
b. Is F obt significant at α = .05; at α = .01
c. Perform post hoc comparisons if necessary.
d. What conclusions can be drawn from the F -ratio and the post hoc comparisons?
e. What is the effect size, and what does this mean?
f. Graph the means.
12. A researcher conducted an experiment on the effects of a new “ drug ” on depression. The researcher had a control group that received nothing, a placebo group, and an experimental group that received the “ drug.” A depression inventory that provided a measure of depression on a 50-point scale was used (50 indicates that an individual is very high on the depression variable). The ANOVA summary table appears next, along with the mean depression score for each condition.
Source df SS MS F
Between groups 1,202.313
Within groups 2,118.00
Total 3,320.313
“ Drug ” Condition Mean n
Control 36.26 15
Placebo 33.33 15
“ Drug ” 24.13 15
a. Complete the ANOVA summary table.
b. Is F obt significant at α = .05; at α = .01
c. Perform post hoc comparisons if necessary.
d. What conclusions can be drawn from the F -ratio and the post hoc comparisons?
e. What is the effect size, and what does this mean?
f. Graph the means.
14. A researcher has been hired by a pizzeria to determine which type of crust customers prefer. The restaurant offers three types of crust: hand-tossed, thick, and thin. Following are the mean number of 1-inch pieces of pizza eaten for each condition from 10 subjects who had the opportunity to eat as many pieces with each type of crust as they desired. The ANOVA summary table also follows.
Source df SS MS F
Subject 2.75
Between 180.05
Error 21.65
Total 204.45
Crust Type Mean n
Hand-tossed 2.73 10
Thick 4.20 10
Thin 8.50 10
a. Complete the ANOVA summary table.
b. Is F obt significant at α = .05; at α = .01
c. Perform post hoc comparisons if necessary.
d. What conclusions can be drawn from the F -ratio and the post hoc comparisons?
e. What is the effect size, and what does this mean?
f. Graph the means.
/////Chapter 12,even exercises pp335 -337.
2. How many independent variables are in a 4 x 6factorial design? How many conditions (cells)are in this design?
4. What is the difference between a cell (condition)mean and the means used to interpret a maineffect?
6. What is the difference between a completefactorial design and an incomplete factorialdesign?
8. Explain the difference between a two-wayANOVA and a three-way ANOVA.
10. Complete each of the following ANOVA summary tables. In addition, answer the followingquestions for each of the ANOVA summarytables:
a. What is the factorial notation?
b. How many conditions were in the study?
c. How many subjects were in the study?
d. Identify significant main effects and interaction effects.
Source df SS MS F
A 1 60
B 2 40
Ax B 2 90
Error 30
Total 35 390
Source df SS MS F
A 2 40
B 3 60
Ax B 6 150
Error 72
Total 83 400
Source df SS MS F
A 1 10
B 1 60
Ax B 1 20
Error 36
Total 39 150
12. A researcher is attempting to determine the effects of practice and gender on a timed task. Participants in an experiment are given a computerized search task. They search a computer screen of various characters and attempt to find a particular character on each trial. When they find the designated character, they press a button to stop a timer. Their reaction time (in seconds) on each trial is recorded. Subjects practice for 2, 4, or 6 hours and are either female or male. The reaction time data for the 30 subjects appear here.
Women Men
2 Hours 12 11
13 12
12 13
11 12
11 11
4 Hours 10 8
10 8
10 10
8 10
7 9
6 Hours 7 5
5 6
7 8
6 6
7 8
Source df SS MS F
Gender 0.02
Practice140.60
Gender x Practice 0.073
Error 28.00
Total 168.70
a. Complete the ANOVA summary table. Calculate the sums of squares, use the preceding data to do so.
b. Is F obt significant at α = .05; at α = .01
c. Perform post hoc comparisons if necessary.
d. What conclusions can be drawn from the F -ratio and the post hoc comparisons?
e. What is the effect size, and what does this mean?
f. Graph the means.
// Chapter 13. Even exercises p 360
2. A psychology professor is interested in whether implementing weekly quizzes improves student learning. She decides to use the weekly quizzes in one section of her introductory psychology class and not to use them in another section of the same course. Which type of quasi-experimental design do you recommend for this study? Why?
< Note: this question, #3, is not to be done but provided so that question 4 below can be answered>
3. If the psychology professor in exercise 2 had access to only one section of introductory psychology, describe how she might use a single-group design to assess the effectiveness of weekly quizzes. Which of the three single-group designs would you recommend?
4. Identify some possible confounds in each of the studies you outlined in your answers to exercises 2 and 3.
6. Give three reasons a researcher might choose to use a single-case design.
8. How does a multiple-baseline design differ from a reversal design?