Lesson 2: Characteristics of Good Sample Surveys and Comparative Studies

Lesson Overview Section

In this lesson, we will add to our knowledge base by explaining ways to obtain appropriate samples for statistical studies.  We will look both at sample surveys and at comparative studies.  For a sample survey,  we want the sample to provide an accurate reflection of the population we are interested in - and random sampling can help.  In a comparative study, we want the groups being studied to provide a fair comparison - and random assignment can help.


After successfully completing this lesson, you should be able to:

  • Distinguish between a population, sample, and sampling frame.
  • Interpret and identify the factors that affect the margin of error.
  • Identify types of probability samples and judgment samples.
  • Apply the "Difficulties and Disasters" in sampling to real world problems.
  • Identify all steps used and issues addressed by the Gallup Poll.
  • Distinguish between randomized experiments and observational studies. 
  • Distinguish between two independent and two dependent (matched paired) samples. 
  • Apply basic terms associated with research studies.