Due: December 1, 2003

1. Use of media – Table 1.

a. Obtain 96% interval estimates for the true mean minutes of media use daily by all Saskatchewan respondents (i) aged 15-24 and (ii) aged 55-64. From these, does it seem likely that 55-64 year olds use the media more than do 15-24 year olds?

Using the data in the last row of Table 1, obtain a 99% interval estimate for the true mean media use daily for all Saskatchewan adults. Explain why the width of this interval differs from the width of the intervals in a.

Table 1. Sample sizes, means, and standard deviations of minutes spent daily using media by Saskatchewan respondents of various ages

Age	Sample Size	Mean Minutes Daily	Standard Deviation of Minutes Daily
15-24	80	168	128
25-34	113	154	123
35-44	115	180	137
45-54	84	179	133
55-64	88	202	160
65-74	81	280	183
75-84	51	336	195
85+	19	334	239
Total	631	207	162

Source: Statistics Canada, General Social Survey, Cycle 12: Time Use, 1998

2. Stress levels. In the Survey of Student Attitudes and Experiences, Fall 1998, students were asked to state how much stress they experienced related to academic performance and to relationships with parents. Responses were coded on a 3-point scale with 1 as minimal stress, 2 as medium stress and 3 as high stress. Results for two samples of undergraduates are shown in Table 2.

For sample 1, obtain a 98% interval estimate for the true mean stress level, for all undergraduates, on the relations with parents issue.
On the academic performance issue, for each of the two samples test whether the mean stress level for all students exceeds 2 (medium stress). Use the 0.05 level of significance. Explain why the result differs for the two samples.
For any such issue, how large a sample size would be required to obtain the true mean level of stress for all undergraduates, correct to within 0.1 points on the 3-point scale, with 99% confidence?

Table 2. Statistics on Stress Levels of Undergraduates for Reasons Related to Academic Performance and Relations with Parents

Sample	Statistic	Academic Performance	Relations with Parents
Sample 1	Mean	2.24	1.45
	Standard Deviation	0.77	0.76
	Sample Size	21	20
Sample 2	Mean	2.36	1.35
	Standard Deviation	0.66	0.61
	Sample Size	697	694

3. Importance of issues. In Unknown Gods: the Ongoing Story of Religion in Canada, (pp. 139 and 143), Reginald W. Bibby of Lethbridge University provides the data in Table 3. Bibby obtained these results from surveys of adults across Canada. Of these data, Bibby notes that physical issues become less important with age, “intellectual growth also ceases to know the importance it did earlier in life” and “the one area in where there is a shift in the direction of increases in importance with the passage of time? God.” Use the data in Table 3 to answer the following:

Obtain interval estimates for the proportion of adults of each of the two age groups who identify spiritual issues as of increased importance.

b. Test whether the proportion of those of age 18-24 who identify sex as of increased importance exceeds one-half.

How large a sample size would be required to obtain the proportion of respondents who identify any issue as of increased importance, correct to within 5 percentage points, 18 times in 20.
Briefly comment on Bibby’s statement using the data in Table 3 and the results from a. and b.

Table 3. Importance of Various Issues to Canadians Aged 18-24 and 35-44

Issue Identified as More Important	Per Cent of each Age Stating Increased Importance
Issue Identified as More Important	Ages 18-24	Ages 35-44
Sex	61%	25%
Intellectual Growth	71%	45%
Spiritual Issues	23%	31%
Sample Size	107	249

4. Computer problems to be handed out on Monday, November 17.