2. Some college professors make bound lecture notes available to their dasses in

Question

2. Some college professors make bound lecture notes available to their dasses in an effort to improve teaching effectiveness. in a study, two groups of students were surveyed-86 student enrolled in a promotional strategy class that required the purchase of lecture notes and 35 students enrolled in a sales/retailing elective that did not offer lecture notes. At the end of the semester, students were asked to respond to the statement, "Having a copy of the lectrure notes was (would be) helpful in understanding the material." Responses were measured on a 9- point semantic difference scale, where 1-strongly disagree and 9-strongly agree. Purchased Lecture Notes n-86 Did Not Purchase Lecture Notes n2 35 A 8.48 s = 0.94 = 7.80 Describe the two populations involved in the comparison Do the samples provide sufficient evidence to conclude that there is a difference in the mean responses of the two groups of students? Test using .01. Construct a 99% confidence interval for (11-12). Interpret the result. would a 95% confidence interval for (A-12). Be narrower or wider that the one you found in part (c). Why? a. b. c. d,

Explanation / Answer

Here are the purchased lecture notes and did not purchase lecture notes are two populations.

Here we have to test the hypothesis that,

H0 : mu1 = mu2 Vs H1 : mu1 not= mu2

where mu1 and mu2 are two population means.

Assume alpha = level of significance = 0.01

Here we use two sample t-test with equal variances.

We can do this test in PH stat.

steps :

Open EXCEL sheet --> Add-Ins --> PHStat --> Two sample tests (Summarized data) --> Pooled variance t test --> Input all the values for population 1 and population 2 --> TestOptions : Two-tail test --> Click on COnfidence interval estimate --> Confidence level : 95% --> ok

99% confidence interval for mu1-mu2 is ( -0.2628, 1.6228).

95% confidence interval for mu1-mu2 is (0.1894, 1.1706)

99% confidence interval is wider interval than 95%.

Pooled-Variance t Test for the Difference Between Two Means (assumes equal population variances) Data Confidence Interval Estimate Hypothesized Difference 0 for the Difference Between Two Means Level of Significance 0.01 Population 1 Sample Data Sample Size 86 Confidence Level 99% Sample Mean 8.48 Sample Standard Deviation 0.97 Intermediate Calculations Population 2 Sample Degrees of Freedom 119 Sample Size 35 t Value 2.6178 Sample Mean 7.8 Interval Half Width 0.9428 Sample Standard Deviation 2.99 Confidence Interval Intermediate Calculations Interval Lower Limit -0.2628 Population 1 Sample Degrees of Freedom 85 Interval Upper Limit 1.6228 Population 2 Sample Degrees of Freedom 34 Total Degrees of Freedom 119 Pooled Variance 3.2264 Standard Error 0.3601 Difference in Sample Means 0.6800 t Test Statistic 1.8882 Two-Tail Test Lower Critical Value -2.6178 Upper Critical Value 2.6178 p-Value 0.0614 Do not reject the null hypothesis -

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