dr.carroll@optonline.net

### Types of Null Hypotheses

Basically, there are two types of null hypotheses with examples for you to use as models with your dissertation samples.

1. Non Directional Null Hypothesis The first type of Null Hypotheses test for differences or relationships with your samples. Examples of null hypotheses are presented below as an illustration of how to state them correctly.

* There is no difference between two sample groups on variable x (as represented by their mean scores).

* There is no difference among three or more sample groups on variable x (as represented by their mean scores).

* There is no relationship between variable x and variable y.

2. Directional Null Hypothesis Sometimes a null hypothesis for differences takes a courageous step and predicts the direction of the difference among samples. The basis for this directional guess should be your knowledge base, evidence in the professional literature or your own experience, and not a superficial guess. You are actually stating which mean score for your samples will be greater when you calculate your statistics.

* Sample Group A will not have a higher mean score than Sample Group B.

* Sample Group A will not have a higher mean score than Sample Group B and Sample Group C.

* There is no positive relationship between variable x and variable y.