You have conducted a study with twelve people. Each person gave two blood samples, one before watching Friday the 13th part 14, and one after watching it. You measure cortisol levels. You subtract these scores (after level minus before level) to measure the effect of the movie on cortisol level. The mean difference is +4 micrograms per deciliter. The difference has a standard deviation of 10. You conduct a one-sample (or paired) t-test. What t value do you get (to two decimal places)?
A) 4.38
B) 4.80
C) 11.55
D) 1.39

Question

Quizplus · Accepted Answer

The t value is calculated using the formula: $ t = \frac{\text{mean difference}}{\text{standard deviation of the difference} / \sqrt{n}} $, where n is the number of pairs. Plugging in the given values: $ t = \frac{4}{10 / \sqrt{12}} = 1.39 $.

You Have Conducted a Study with Twelve People