In response to a reported outbreak with a p-value of 0.01, what decision should be made at alpha = 0.05?

• A. Do not reject the null hypothesis
• B. Reject the null hypothesis
• C. Accept the alternative hypothesis
• D. Data are insufficient to decide

Answer: (B)

In hypothesis testing, you compare the p-value to your chosen significance level to decide whether to reject the null. A p-value of 0.01 means that if there were no real outbreak effect, you'd expect to see results as extreme as observed only about 1% of the time. With a significance level of 0.05, any p-value smaller than 0.05 is considered statistically significant. Since 0.01 is less than 0.05, you reject the null hypothesis. This indicates evidence against no outbreak effect at the 5% level. It’s not about proving the alternative; it’s about concluding that the observed result is unlikely under the null. Here, the data are sufficient to decide at this significance level, leading to rejecting the null.