Hypothesis

A hypothesis is a statement that predicts the relationship between variables

Null Hypothesis

The null hypothesis is a statement that there is no difference or no relationship between

variables.

This is a

null hypothesis.

It states that the mean from group one is equal to the mean from group two.

Alternate Hypothesis

The Alternate hypothesis is a statement that there is difference between variables.

This is a

alternate hypothesis.

It states that the mean from group one is not equal to the mean from group two.

The statement “… that the mean from group one is not

equal to the mean from group two”

signifies the alternate hypothosis is

non-directional.

That means the mean of group 1 can be greater than the mean of group 2, or the mean of group 1 can be less than the mean of group2.

This is a non-directional test.

A non-directional test is also called a

two-tailed test.

Sometimes we want to test a hypothesis in one direction or another.

These tests use a directional test.

A directional test is also called a

one-tailed test.

•Mathematically, a non-directional alternate hypothesis which would use a one-tailed would be look like this:

This statement says the mean of group 1 is greater than the mean of group 2.

This statement says the mean of group 1 is less than the mean of group 2.

Examples of alternate hypothesis which would use a one-tailed test.

Men are taller than women.

Blondes have more fun.

Women are more prone to osteoporosis than men.

Examples of alternate hypothesis which would use a two-tailed test.There is a difference in height between men and

women.

There is a difference in the amount of fun blondes have compared to brunettes and redheads (for both men and women).

There is a difference in the incidence in osteoporosis between men and women.