Question

# The situation… • A 12-month email study looked at the click-through responses triggered by two versions...

 The situation… • A 12-month email study looked at the click-through responses triggered by two versions of email, Version A and Version B. • In all 24 distributions (12 for Version A; 12, Version B) emails were drawn randomly. • People receiving A or B versions were unrelated (randomly selected every time for both version of the email). • The researchers had no idea which version would trigger more clicks. • Alpha was set at p <.05. Month Email Response-Rate Study Group A Group B January 36 36 February 35 25 March 24 29 April 23 37 May 29 37 June 12 23 July 18 27 August 12 21 September 14 24 October 24 33 November 25 32 December 33 40 Mean 23.75 30.33 SD 8.51 6.37 Variance 72.39 40.61 t test 0.044 Effect Size -0.77 Using this scenario and the data above, respond to all of the following items: 1. What type of t test would you use? Why?

-0.77

Here we need to use two sample independent t-test. Because the sample is taken randomly from both the groups.

next we need to decide "is it pooled t-test or unpooled t-test?"

For this we need to test equality of two variances.

Null hypothesis:

H0 : both the variances are equal

Alternative hypothesis:

Ha : They are different.

Let's use minitab:

Step 1) Click on Stat >>>Basic Statistics >>>2-Variances ...

Fill the necessary information and then click on Option again fill the necessary information.

Look the following image:

Then click on OK again Click on OK , so we get the following output:

From the above output, the p-value is as follow:

p-value = 0.352

Since p-value > 0.05 we fail to reject the equality assumption of two populations.

So that the pooled procedure more appropriate in this situation.

that is we need to used pooled t-test.

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