# Null hypothesis (3 of 4)

Despite the "null" in "null hypothesis," there are
occasions when the parameter is not hypothesized to be 0.
For instance, it is possible for the null hypothesis to be
that the difference between population means is a particular
value. Or, the null hypothesis could be that the mean SAT
score in some population is 600. The null hypothesis would
then be stated as: H

_{0}: μ = 600. although the null hypotheses
discussed so far have all involved the testing of hypotheses
about one or more population means, null hypotheses can
involve any parameter. An experiment investigating the

correlation between job
satisfaction and performance on the job would test the null
hypothesis that the population correlation (ρ) is 0. Symbolically, H

_{0}:
ρ = 0.

Some possible null hypotheses are given below:

H

_{0}: μ=0

H

_{0}: μ=10

H

_{0}: μ

_{1} -
μ

_{2} = 0

H

_{0}: π = .5

H

_{0}: π

_{1} -
π

_{2 } = 0

H

_{0}: μ

_{1 }= μ

_{2} = μ

_{3}
H

_{0}: ρ

_{1}-
ρ

_{2}= 0