AP Statistics: Chapter 4 - Data Generation Techniques

Overview

• Focus: Learn about data generation techniques.
• Sections Covered: Section 4.1 - Samples and Surveys.

Key Topics

Population vs. Sample

• Population: Entire group of interest.
• Sample: Subset of the population.
  • Census: Data from entire population (e.g., ages of all US Presidents).
  • Sample: Smaller group, used to make inferences about the population.

Sampling Techniques

1. Define the Population: Identify group of interest.
2. Determine Data Type: Numerical or categorical.
3. Data Collection Mechanism: Utilize surveys, etc.
4. Sample Selection Method:
   • Random Sample: Names from a hat, random number generator.

Avoiding Bias in Sampling

• Convenient Sample:
  • Example: Surveying beachgoers about recycling may not be representative.
  • Potential for bias as the sample might not represent the broader population.
• Voluntary Response:
  • Example: Online surveys may attract only those with strong opinions.
  • Leads to biased data and non-representative results.

Preferred Sampling Methods

• Simple Random Sample (SRS):
  • Equal chance for every individual and group to be selected.
  • Use low-tech (drawing names) or high-tech (calculators, Table D) methods.
• Stratified Random Sample:
  • Separate population into strata based on shared characteristics.
  • Perform SRS within each stratum.
• Cluster Sampling:
  • Often geographically based.
  • Randomly select clusters, then survey all individuals within chosen clusters.

Considerations for Effective Sampling

• Avoid Bias:
  • Avoid convenience and voluntary response methods.
  • Ensure sample is large enough to be representative.
• Non-response Issues:
  • Handling under coverage and non-response is critical.

Potential Bias Sources

• Under Coverage:
  • Some population members cannot be chosen (e.g., prisoners, unlisted phone numbers).
• Non-response:
  • When individuals cannot be contacted or refuse participation.
• Response Bias:
  • Systematic pattern of responses due to question wording.

Conclusion

• Met lecture objectives.
• Next section (4.2) will cover experiments.