Question 1
A questionnaire is sent to 10,000 persons. 5000 responded to the questionnaire. 3000 of the respondents say that "They love chocolate ice cream." We conclude that 60% of people love chocolate ice cream. What is wrong with this survey?Question 2
"7 out of 10 dentists recommend Brand X toothpaste." This finding is based on the results of a survey of 10 randomly selected dentists. What is wrong with this survey?Answer 1
This is not a random sample. The survey is based on voluntary, self-selected responses and therefore has serious potential for bias.Answer 2
The sample was too small.