Lesson 7: Census, Sampling, Surveys and Inference

September 23, 2019

Review:

• Exam 1 Results
• Starfish reporting
• Exam solutions

Presentation:

• Census and Sampling
  • Census = attempt to count entire population
    • US Census every 10 years
    • Most costly non-military federal government operation (except bailing out Wall Street)
  • Sample = gather info from a portion of the population
    • Sample Types
      • Voluntary response sample
        • Complete an optional survey
        • Inherent bias
        • Example: Google Survey
      • Simple random sample
        • select from a population
        • each individual has equal chance of being selected
        • Example: random selection of subset of enrolled students
      • Stratified random sample
        • divide population into groups or strata
        • random sampling, equal chance of selection within each group
        • Example: random selection within major (30% CIS, 35% Mgmt, 35% Econ)
  • Video: Census and Sampling
• Samples and Surveys
  • Toward Statistical Inference
    • Population parameters
    • Sample statistics
    • Sampling distribution
    • Bias and Variability
      • to reduce bias, use random sampling
      • to reduce variability, use larger sample sizes (p. 215)
    • Margin of Error Calculator
  • Video: Samples and Surveys

Activity:

• 2020 Iowa Caucus
• Choose a recent poll
• Find the sample size
• Estimate the population size
• Calculate margin of error using 95% confidence

Assignment:

• Watch Designing Experiments