This page gives you the key ideas to recognise before you start a question. The full course then takes you through the method, exam-style practice and fully worked solutions.
State H₀ and H₁
The null hypothesis represents the model being tested. The alternative hypothesis reflects the claim or direction in the question.
Choose the tail
Words such as increase, decrease or different determine whether the alternative is one-tailed or two-tailed.
Use the significance level
The significance level controls how unusual the result must be before H₀ is rejected.
Conclude in context
Say whether there is sufficient evidence for the alternative claim. Avoid saying that a hypothesis has been “proved”.
Worked example: conclusion language
If the observed result lies in the critical region:
Reject H₀.
There is sufficient evidence, at the stated significance level, to support H₁ in the context of the question.
Reject H₀.
There is sufficient evidence, at the stated significance level, to support H₁ in the context of the question.
Common mistakes to avoid
- Writing hypotheses without defining the parameter.
- Using the wrong tail because the wording of H₁ was not checked.
- Saying “accept H₀” or “H₁ is proven” instead of using evidence-based language.