A Set of Sample Scores from an Experiment Has an N

Multiple Choice

A set of sample scores from an experiment has an N = 28 and a mean = 52. H 1 is directional, predicting an effect of the independent variable which decreases the magnitude of the dependent variable. H 0 asserts the sample is a random sample from a population of scores where µ = 55 and s = 12. a = 0.05_{1 tail}. Using the z test to analyze the data, what is the correct conclusion regarding H 0 ?

A) reject H 0 ; the independent variable has a real effect
B) retain H 0 ; we cannot conclude that the independent variable has a real effect
C) accept H 0 ; the independent variable has no effect
D) reject H 0 ; the independent variable has no effect