Descriptive vs Inferential Statistics

Descriptive statistics are there to describe a sample. That’s pretty straightforward. You simply take a group that you’re interested in, record data about the group members, and then use summary statistics and graphs to present the group properties. With descriptive statistics, there is no uncertainty because you are describing only the people or items that you actually measure. You’re not trying to infer properties about a larger population.

Inferential statistics takes data from a sample and makes inferences about the larger population from which the sample was drawn. “Making inferences” means predicting, or estimating unknown population values, so there will always be some level of uncertainty associated with inferential statistics.