You want to compare the daily number of hits for 2 different

You want to compare the daily number of hits for 2 different MySpace page designs that advertise your indie rock band. You assign the next 30 days to either design A or design B, 15 days each.

a) Would you use a one-sided or a two-sided significance test for this problem? Explain.

b) If you use a t table to find the critical value, what are the degrees of freedom using the second approximation?

c) If you perform the significance test using alpha = 0.05, how large must the t-statistic be to reject the null hypothesis that the two designs result in the same average number of hits?

d) If the t-statistic for comparing the mean hits was 2.18, what p-value would you report? What would you conclude using alpha = 0.05?

Solution

Sol)

a) Here n1=15 andd n2=15

we use two tailed test test.

Null hyp: There is no difference between means of two designs.

Alternative hyp: There is a significance difference between means of two designs (two tail)

b) The critical value for t test is with (n1+n2 - 2) = 28 df

c) The critical value at 5% level with 28 d.f is 2.048

if t cal < t critical value we accept the null hypothesis.

If t cal > t critical value we reject the null hypothesiss.

D)

If t cal = 2.18 and alpha=0.05

Then p value is 0.038 .

Hence p<alpha value hence we reject the null hypothesis.