Author Question: Why is the null hypothesis in a correlation hypothesis test usually that the population correlation ... (Read 42 times)

asmith134 · **on:** Jun 20, 2018

Why is the null hypothesis in a correlation hypothesis test usually that the population correlation is zero?

What will be an ideal response?

Question 2

Why would a correlation of .5 be just as useful as a correlation of .5?

What will be an ideal response?

jaymee143 · **Reply #1 on:** Jun 20, 2018

Answer to Question 1

It is partly due to tradition, but there's also a reason. We hypothesize that the population correlation is zero because (1) correlation = 0 is the midpoint between positive and negative correlations; and (2) zero correlations between variables are important; they indicate that the two variables are independent.

Answer to Question 2

Because it is the size of the correlation and not the sign that indicates the magnitude of the relationship between the variables. Both .5 and .5 indicate 25 percent shared variance between the variables.