Alternative Hypothesis (H1 or Ha): Definition, Characteristics & Pharmaceutical Example

Definition

• The alternative hypothesis is a statement that contradicts the null hypothesis and represents the hypothesis that there is an effect or a difference.

• It is what the researcher aims to provide evidence for.

Characteristics

• Indicates an Effect: The alternative hypothesis suggests that any observed effect is real and not due to random chance.

• Directionality: It can be one-sided (one-tailed) or two-sided (two-tailed), depending on the research question.

• Formulation: It is often formulated to include inequality signs (e.g., ≠, <, >).

Pharmaceutical Example

• Continuing with the clinical trial example, the alternative hypothesis might be:
  

• This states that the mean outcome for the treatment group is different from that of the placebo group, indicating that the new drug has an effect.