AP® Statistics · Unit 3 · Topic 3.7
Stating a Conclusion in Context
A statistics conclusion compares the p-value to alpha and states, in the context of the real question, whether there is convincing evidence for the alternative claim. It never claims the null is proven true.
A hypothesis test ends with a decision, and that decision has to be written in a specific, defensible way. You compare the p-value to alpha. If the p-value is smaller, the result would be rare under the null hypothesis, so you reject H0 and say there is convincing evidence for the alternative. If the p-value is larger or equal, the result isn't surprising enough, so you fail to reject H0 and say there is not convincing evidence for the alternative. Either way, the sentence must name the p-value, name alpha, state the decision, and tie it back to the actual question being studied, not just abstract symbols.
The reason context matters is that a bare 'reject H0' means nothing to anyone outside the room. Naming the real quantity, like the true proportion of voters favoring a policy, turns a statistical ruling into something useful. The language also has to respect what a p-value actually measures: strength of evidence, not certainty. That is why you never write 'accept H0' or 'proves the null is true' — failing to reject just means the data didn't give you enough reason to abandon the null, not that the null has been confirmed.
This phrasing connects directly to confidence intervals. A two-sided test at alpha 0.05 and a 95 percent confidence interval are two views of the same evidence: if the null value falls outside the interval, you'd reject H0 at alpha 0.05, and if it falls inside, you'd fail to reject. Writing conclusions well is the last step of the whole inference process, after you've checked conditions and calculated the statistic.
Key terms
- p-value
- The probability of getting a result at least as extreme as the one observed, assuming the null hypothesis is true.
- alpha
- The significance level, a threshold chosen in advance that decides how small the p-value must be to reject H0.
- reject H0
- The decision made when the p-value is less than alpha, interpreted as convincing evidence for the alternative claim.
- fail to reject H0
- The decision made when the p-value is at least alpha, meaning there is not convincing evidence for the alternative claim.
- context
- The real-world quantity or question the test addresses, which must appear in the written conclusion.
Watch it explained
- How it worksHow do you turn a p-value of 0.008 into a sentence about the real-world question?
- Worked exampleShow me the full conclusion for a p-value of 0.21 at alpha 0.05 about voter support.
- Common mistakeWhy isn't 'we accept the null hypothesis' ever a correct thing to write?
- Ties togetherHow does a two-sided test at alpha 0.05 line up with a 95 percent confidence interval?
Check yourself
End of topic.