061003L - THE NULL AND THE ALTERNATIVE HYPOTHESES

Lecture for PPSD session for Year 1 Semester 1 medical students on 3^rd October 2006 by Professor Omar Hasan Kasule Sr.

1.0 HYPOTHESES AND THE SCIENTIFIC METHOD

The scientific method consists of hypothesis formulation, experimentation to test the hypothesis, and drawing conclusions.

Hypotheses are statements of prior belief. They are modified by results of experiments to give rise to new hypotheses. The new hypotheses then in turn become the basis for new experiments.

2.0 NULL HYPOTHESIS (H₀) & ALTERNATIVE HYPOTHESIS (H_A):

The null or research hypothesis, H₀, states that there is no difference between two comparison groups and that the apparent difference seen is due to sampling error.

The alternative hypothesis, H_A, disagrees with the null hypothesis. H₀ and H_A are complimentary and exhaustive.

A hypothesis can be rejected but cannot be proved. A hypothesis cannot be proved in a conclusive way but an objective measure of the probability of its truth can be given in the form of a p-value.