Lab 2: Statistical Definitions, Sampling Methods, and Bias

Statistical Definitions

Definitions of key statistical terms

  • Individual: Single entity being studied.

  • Variable: Characteristic or measurement of an individual.

  • Sample: Subset of the population.

  • Statistic: Number summarizing the sample.

  • Population: Entire group of interest.

  • Parameter: Number summarizing the population.

Study Designs

  • Experiment: Study where treatment groups are randomly assigned.

  • Observational Study: Study where groups are self-selected.

Sampling Methods

Sampling methods definitions and examples

  • Simple Random Sample: Randomly selecting individuals from the population.

  • Cluster Sample: Selecting all individuals from randomly selected subgroups.

  • Stratified Sample: Selecting some individuals from all subgroups randomly.

  • Multi-Stage Sample: Selecting some individuals from some subgroups randomly.

  • Convenience Sample: Selecting the easiest available individuals; non-random.

Types of Survey Bias

Types of bias in sample surveys

  • Undercoverage: Individuals in the population cannot be selected for the sample.

  • Nonresponse: Individuals selected for the sample provide no information.

  • Misleading response: Individuals in the sample provide inaccurate information.

  • Interviewer effect: The person asking the questions influences the responses.

  • Question order: Earlier questions influence responses to later questions.