Null Hypothesis
The default assumption that there is no relationship, no difference, or no effect between variables.
What is Null Hypothesis?
The null hypothesis (denoted as H0) is a specific, testable statement used in statistics predicting that any observed difference or relationship in the sample data is due to random chance rather than a true underlying effect.
Why Null Hypothesis Matters
It provides a baseline for statistical testing. The entire framework of hypothesis testing is built around trying to reject this default assumption with sufficient evidence.
How to Interpret
You never 'prove' the null hypothesis true; you only 'fail to reject' it due to lack of evidence.
Example
If testing whether tutoring improves test scores, the null hypothesis states: 'Tutoring has no effect on test scores (the mean score of tutored students equals the mean score of untutored students).'
Common Mistakes
- Accepting the null hypothesis as absolute truth when p > 0.05.
- Confusing the null hypothesis with the research (alternative) hypothesis.