Inference
Statistical inference refers to statistical techniques for obtaining information about a population parameter (or parameters) from a random sample. There are two branches of inference:
Estimation
Point estimates and confidence intervals give answers to questions of the form:
What parameter values would be consistent with the sample data?
Hypothesis tests
This chapter deals with a related type of question:
Are the sample data consistent with some statement about the parameters?
Errors and strength of evidence
A single random sample can rarely provide enough information about a population parameter to allow us to be sure whether or not any statement (hypothesis) about that parameter will be true. The best we can hope for is an indication of the strength of the evidence against it.