4.3 - Introduction to Inferences

What Ellie is trying to do is called statistical inference, yielding probability statements about the population of interest based on a sample data.

Types of Statistical Inference

There are two types of statistical inferences: Estimation and Statistical Tests.


Use information from the sample to estimate (or predict) the parameter of interest.

For instance, Ellie’s use of the results from her sample of runners to estimate (or predict) the true number of miles run by marathon runners.

Statistical Tests

Use information from the sample to determine whether a certain statement about the parameter of interest is true. Statistical tests are also referred to as hypothesis tests.

For instance, Ellie might want to test a claim that marathon runners run 50 miles per week. She wants to determine whether that statement is supported by her sample data.