Unrepresentative Sample

Definition:

The examples used in an inductive inference are relevantly different from the population as a whole.

Examples:

(i) To see how Americans will vote in the next election we polled a hundred people in Grenwich Village. This shows conclusively that the Democratic Party will sweep the polls. (People in Grenwich Village tend to be more liberal, and hence more likely to vote Democratic, than people in the rest of the country.)

(ii) The apples on the top of the box look good. The entire box of apples must therefore be good. (Of course, the rotten apples may be hidden beneath the surface where the moisture and darkness facilitate rotting.)

Proof:

Show how the example cases are relevantly different from the population as a whole, then show that because the examples are different, the conclusion does not follow.

References:

Barker: 188, Cedarblom and Paulsen: 226, Davis: 106

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