Section 1.3 Summary

1. A random sample is a sample for which every element has an equal chance of being included. A random sample can minimize many potential biases, which could lead to incorrect generalizations about the population.
2. Other sampling methods include stratified sampling, systematic sampling, cluster sampling, and convenience sampling.
3. When constructing a survey, avoid selection bias and follow the five factors for good questionnaire design.
4. Two types of statistical studies are used: experimental studies and observational studies. In an experimental study, researchers investigate how varying the predictor variable affects the response variable. It is not always possible to conduct an experimental study, however, and sometimes an observational study is used instead.