Key Concepts

• Two measurements (samples) are drawn from the same pair of individuals or objects.
• Differences are calculated from the matched or paired samples.
• The differences from the sample are used to conduct the hypothesis test.
• Either the matched pairs have differences that come from a population that is normal or the number of differences is sufficiently large (more than 30).
• The distribution that is used to conduct the hypothesis test on the differences is a t-distribution.

Glossary

Degrees of Freedom (df): the number of objects in a sample that are free to vary.

Matched or Paired Samples: when data is gathered from two similar subjects (or the same subject) to create a pair of data.