Answer “true” or “false” to the following statements:

­1. If a sample is very large, it need not be randomly selected.

2. If a population is randomly arranged, a sample obtained by selecting every tenth member would be a random sample.

3. If a sample is randomly selected, the larger the sample is, the more closely it replicates the population.

­4. To ensure the same precision, a population of 1 million would require a much larger random sample than would a population of 100,000.

5. In general, if sample A is twice as large as sample B, then the sampling error for A is one-half that for B.

6. When a sample consists of human beings, the purpose for which the sample is taken can affect the outcome.

­7. The personal interaction between a surveyor and a respondent can affect the outcome of a survey.

8. The mean value of a set of data is the value that occurs with the greatest frequency.

9. The median value of a set of data is the middle point when the data are arranged in ascending order.

10. The modal value of a set of data is the arithmetical average.

11. If one needed to know whether a sizable portion of a group were above or below a certain level, the most useful sense of average would be mode.

12. Data reflecting the results of a random sample conform fairly closely to the normal probability distribution.

­13. If a set of data conforms to the normal probability distribution, then the mean, median, and mode have the same value.

14. Range, variance, and standard deviation are measurements of dispersion.

15. Statements about averages often present an incomplete picture, lacking information about the dispersion.

­16. Data reflecting the size of full-grown horses would exhibit greater dispersion than would data reflecting the size of full-grown dogs.

17. The visual impression made by graphs can be exaggerated by changing one of the scales while leaving the other unchanged.

18. Data reflecting a 100 percent increase in housing construction could be accurately represented by a pictogram of two houses, one twice as high as the other.

­19. If a certain quantity is increased by 10 percent and later decreased by 10 percent, the quantity is restored to what it was originally.

20. Expressing profits as a percentage of sales volume presents an honest picture of the earnings of a corporation.