The mean percentage of correctly recalled words was

Question

Problem 1:

You've recently began to notice the "filler" words, such as "um" and "ah", that people use when they speak.You suspect that there may be gender differences in how often people use these words. To test this idea you compare the frequency of occurrence for "um" in a sample of 14 males and 14 females speaking extemporaneously for 4 minutes on the topic of their family history. What should you conclude based on these data? Explicitly indicate all the steps in your evaluation of these data. (Data at right.)

Number of "um" utterances
Females		Males
4		3
5		7
6		5
5		8
7		6
6		4
7		4
4		5
6		5
5		9
6		5
4		5
6		4
3		5

Problem 2:

A professor thinks that in-class attendance for courses that also have a CUOL section, such as PSYC/NEUR 2002 (i.e., where section B is the in-class section and section V is the CUOL version) will be less in the in-class section compared to courses that do not have a companion CUOL section. Midway through the term she obtains the percentage of students attending 12 in-class sections that also have corresponding CUOL sections. She compares these percentages to the mean percentage of students attending all courses that same day that do not have a corresponding CUOL section. The mean attendance for all the nonCUOL courses is 70%, with a SD = 5.6%. Do the results support the professor's hypothesis ? Explicitly indicate all the steps in your evaluation of these data. (Data at right; % of attendance refers to attendance in the in-class sections for courses that also have a corresponding CUOL section.)

Course	% of  attendance
1	78
2	47
3	62
4	56
5	59
6	72
7	79
8	61
9	44
10	67
11	71
12	59

Problem 3:

A cognitive psychologist was interested in whether lists of words consisting of high frequency words versus lists consisting of low frequency words would be better remembered. Sixteen participants were each presented 12 lists of words, with six lists consisting of high frequency words and six lists consisting of low frequency words. The mean percentage of correctly recalled words was calculated for each type of list for each participant. From the information provided on the right, does any difference exist between the recall of high versus low frequency words?

	Mean percentage of words recalled
Participant	High frequency word lists	Low frequency word lists
1	66.98	59.04
2	71.86	70.33
3	69.76	58.31
4	72.14	54.63
5	79.91	62.63
6	67.00	60.02
7	67.93	66.64
8	73.34	52.76
9	81.51	52.47
10	73.40	50.10
11	67.61	54.01
12	68.34	65.15
13	83.76	52.07
14	77.43	78.04
15	65.18	65.62
16	78.89	59.31