Question

Performance scores on a motor skills task form a normal distribution with μ=20 and σ=4. A psychologist is using this task to determine the extent to which increased self-awareness affects performance. The prediction for this experiment is that increased self-awareness will reduce a subject’s concentration and result in lower performance scores. A sample of n=16 subjects is obtained, and each subject is tested on the motor skills task while seated in front of a large mirror. The purpose of the mirror is to make the subjects more self-aware. The average score for this sample is x̅=15.5. Test the psychologist’s prediction with α=.05. Make sure to include the standard four steps (hypothesis, criteria, calculation, conclusion)

Answer 1

Given ; Sample size = n = 16

Sample mean =

Population standard deviation=

Significance level=

Population mean =

Hypothesis : Vs

The test statistic is ,

Critical value :

Decision : Here ,

Therefore , reject the null hypothesis.

Conclusion : Hence , the population average score reduce.