E. Pierre. The latest AARP survey says that American seniors are living longer and healthier lives than ever before. Old people make up around 10 percent of American society, and respondents to the AARP survey turned out to be both significantly healthier, and to have on average lived considerably longer than a demographically identical group surveyed only five years previously. I think this survey is reliable, because it is based on responses from nearly the entire membership of the AARP, which is of course composed entirely of seniors, and was supervised by the best statistical survey analysts available.
Sonya. You're forgetting one thing. The AARP only makes up just over 5 percent of the American population. How can you make any kind of serious generalization based on a sample that is just 5 percent of the population?


Pierre     1. An AARP survey says that American seniors are living longer and healthier lives than ever before.
              2. The survey was based on responses from nearly the entire membership of the AARP.
              3. The AARP is composed entirely of seniors.
              4. The survey was supervised by the best statistical survey analysts.                                            
              C. American seniors are living longer and healthier lives than ever before.              DIRECT

Sonya     1. The AARP makes up just over 5 percent of the American population.
               2. 5 percent is too small to make a representative sample.                                           
              C. The AARP survey is unreliable.                                                              COUNTER

Connection: Pierre gives a direct argument
                   Sonya gives a counter argument

Analysis:   Pierre bears the burden of proof. [He supports a positive conclusion, whereas Sonya supports the null hypothesis.]

Pierre   Generalization Argument.
            Population: American seniors
            Sample:  AARP members
            Age: current
            Size: 5% of Americans.

Evaluation: Sonya makes two mistakes. First, she thinks that 5 percent is too small a sample. In a properly conducted study, 5 percent is plenty. However, Sonya makes another mistake. Pierre's generalization does not cover the whole American population. It just covers the 10 percent that are seniors. 5 percent is half of 10 percent, so Pierre's sample is 50 percent of his population, not 5 percent.

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