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What is a hypothesis test?

Learning outcomes:

On watching this video, students should be able to:

  1. Explain why we use a hypothesis test and differentiate it from the information contained in a confidence interval.
  2. Write down the null hypothesis given a research question or study outline.
  3. List the three main steps of a hypothesis test.
  4. Explain what a test statistic is and how it is used it to calculate a p-value.
  5. Explain the term significance, and how a hypothesis test is often used to make a decision about whether to reject or fail to reject the null hypothesis.
  6. Explain why we either reject or fail to reject the null hypothesis and do not say that we have proved the null hypothesis.
  7. Interpret a p-value as a continuous measure of the strength of evidence against the null hypothesis, and explain why the dichotomous interpretation of p-values as significant or not significant is arbitrary and generally should be avoided.
  8. Explain the difference between a one-sided (one tailed) and two sided (two-tailed) hypothesis test and why a two-tailed test is the default.
  9. Describe the difference between statistical and practical (clinical) significance and link this why it is often useful to report both a p-value and a confidence interval when reporting results.