Problem Set 5 Solutions

1. A professor is wondering whether allowing students to use their notes during tests improves performance. She uses one of her classes as a control group and does not allow them to use their notes, and she allows her second class to use their notes while taking their exams. Below are the grades for each 12 person class. Is there a difference in grades due to being allowed to use notes?

 

Control Class   Open Notes Class

78                             90

72                             88

76                             87

74                             85

60                             65

90                             65

55                             97

72                             92

87                             87

86                             73

73                             86

62                             85

Research Problem (2 points):

Statistical Hypotheses (4 points):

Decision Rule (4 points):

Reject the null hypothesis at the .05 level of significance if t is less than _____, given ______ degree of freedom.

Calculations (copy and paste your Jamovi output here or upload a separate file with your outputs to Blackboard.) (5 points)

Decision (5 points):

Interpretation (5 points):

2. A developmental psychologist is interested in whether there is a difference in anxiety between parents and their children. A study is done involving one parent and the oldest child for each of 15 families, measuring the anxiety in each member of the pair. The data are below with higher scores indicating more anxiety. Do parents and their children differ?

 

Family    Parent     Child

1                 8           6

2                 4           5

3                 5           5

4                 6           5

5                 3           8

6                 2           6

7                 6           7

8                 7           7

9                 7           8

10               7           9

11               8           8

12               9           6

13               5           3

14               4           2

15               4           3

Research Problem (2 points):

Statistical Hypotheses (4 points):

Decision Rule (4 points):

Reject the null hypothesis at the .05 level of significance if t is greater than or equal to _____ or less than or equal to __, given __ degree of freedom.

Calculations (copy and paste your Jamovi output here or upload a separate file with your outputs to Blackboard.) (5 points) Decision (5 points):

Interpretation (5 points):

3. A researcher hypothesizes that there has been an increase in felony prison sentences over the past 5 years. In 2013 the average prison sentence was 9 years. The researcher selects a random sample of prisoners currently serving prison terms for felonies and finds that they have the following prison sentences. Has the average amount of time that people are sentenced for felony convictions changed in the last 5 years?

Prison Sentences in Years

11, 13, 14, 15, 8, 9, 10, 11, 11, 10, 11, 12, 13, 14, 15, 7, 8

Research Problem (2 points):

Statistical Hypotheses (4 points):

Decision Rule (4 points):

Reject the null hypothesis at the .05 level of significance if t is greater than __________, given ___ degrees of freedom.

Calculations (copy and paste your Jamovi output here or upload a separate file with your outputs to Blackboard.) (5 points) Decision (5 points):

Interpretation (5 points):

4. Researchers have a hypothesis that older siblings tend to be more extroverted than their younger siblings. They collected data between 14 pairs of same sex siblings, and found the following extraversion scores. Is there a difference between how extraverted older and younger siblings are? (Extraversion is measured on a 50 point scale with higher scores indicating more extraversion.)

 

Sibling Pair     Older Sibling   Younger Sibling

1                          48                40

2                          42                32

3                          36                25

4                          29                19

5                          45                36

6                          22                14

7                          25                15

8                          35                24

9                          45                37

10                        50                44

11                        36                 29

12                        24                15

13                        33                34

14                        39                31

Question 4

Research Problem (2 points):

Statistical Hypotheses (4 points):

Decision Rule (4 points):

Reject the null hypothesis at the .05 level of significance if t is greater than _____, given __ degrees of freedom.

Calculations (copy and paste your Jamovi output here or upload a separate file with your outputs to Blackboard.) (5 points)

Decision (5 points):

Interpretation (5 points):