Question

Is there any systematic tendency for part-time college faculty to hold their students to different standards than do full-time faculty? The article “Are There Instructional Differences Between Full-Time and Part-Time Faculty?” (College Teaching, 2009: 23-26) reported that for a sample of 125 courses taught by full-time faculty, the mean course GPA was 2.7186 and the standard deviation was 0.63342, whereas for a sample of 88 courses taught by part-timers, the mean and standard deviation were 2.8639 and 0.49241, respectively. Does it appear that true average course GPA for part-time faculty differs from that for faculty teaching full time? Test the appropriate hypothesis at significance level 0.01. Evaluate the hypothesis using both critical value and p-value.

Answer 1

The test hypothesis is

This is a two-sided test because the alternative hypothesis is formulated to detect differences from the hypothesized difference in mean values on either side.

Now, the value of test static can be found out by following formula:

Using Excel's function =T.DIST.2T(|t0|,n-1), the P-value for t0 = -1.8019 in an t-test with 211 degrees of freedom can be computed as

Since P = 0.07299 > 0.01, we fail to reject the null hypothesis

Degrees of freedom on the t-test statistic are n1 + n2 - 2 = 125 + 88 - 2 = 211

Since , we fail to reject the null hypothesis .

Yes it is appear that true average course GPA for part-time faculty differs from that for faculty teaching full time