Question

You measured scores of people taking two different versions of an exam. 26 people took version A (mean = 87, SD = 7.04), and 26 took version B (mean = 84, SD = 9.16). Given these data, calculate the pooled standard deviation for an independent sample t-test. Round your answer to two decimal places.

Answer 1

The formula for the pooled standard deviation is given by:

where

are the sample sizes of first and second group respectively;

are the standard deviation of first and second group respectively; and

is the pooled standard deviation.

[Here we denote the people who took version A as Group 1 and people who took version B as Group 2 respectively]

Now, we are given that:

Thus, the pooled standard deviation is given by:

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