6-1 Journal: Rejecting and Failing to Reject the Null Hypothesis
What is the difference between failing to reject the null hypothesis and having evidence
to support the alternative hypothesis?
Failing to Reject the Null Hypothesis
occurs when the
statistical test's p-value is higher than the alpha, the level at which a difference is considered
significant. Researchers fail to reject the null hypothesis when the p-value exceeds the
predetermined significance level (alpha), which is typically set at 0.05 or 0.01. This indicates that
not enough statistical data exists to draw a conclusion about the existence of a significant
difference or effect.
Having Evidence to Support the Alternative Hypothesis
occurs whenever
the p-value is below the alpha, the predetermined level of significance. This outcome suggests
that the data provides sufficient statistical evidence to reject the null hypothesis in favor of the
alternative hypothesis. It is crucial to understand that "failing to reject" simply indicates that
there is insufficient evidence to support the alternative hypothesis; it does not demonstrate that
the null hypothesis is true. Conversely, "having evidence to support the alternative hypothesis"
indicates that the data provides support for the claim researchers are investigating.
I work as a research assistant, conducting clinical trials for new chemotherapy treatment
drugs for cancer patients with specific cancers. The null hypothesis assumes that the new
chemotherapy drug is not more effective than the existing standard of care drug. The alternative
hypothesis, which suggests that the new chemotherapy drug is more effective than the standard
of care drug. During the clinical trials, we evaluate to see if the new chemotherapy drug is more
effective than standard of care chemotherapy drug. We put our patient also known as “subjects”
(due to PHI) into a database to be randomized to see if the patient is eligible for the new
chemotherapy drug or ineligible and will receive the placebo drug. This is the predetermined
threshold set at 0.05 in my case. It represents the probability of making a Type I error rejecting
