T SCORE and Effect size

Question

A professor believes the students in a statistics class this term are more creative than most other students attending the university. A previous study found that students at the university had a mean score of 35 on a standard creativity test, and the current class has an average score of 40 on this scale with an estimated population standard deviation of 7. The standard deviation of the distribution of means is 1.63.

 

Using this scenario what is the T score ? The effect size? and 

Answer 1

Let X = the current class average score.

 

 

t-score: t = (X - μ) / (σ/√n) = (40 - 35) / 1.63 = 3.07

 

 

This is over 3 standard deviations away, so it gives support to the professor's belief that the students are more creative than other classes.

 

 

effect size: (X - μ) / σ = (40 - 35) / 7 =  0.714