Every week during the Vietnam War, a body count (number of enemy killed) was reported by each army unit. The last digits of these numbers should be fairly random. However, suspicions arose that the counts might have been fabricated. To test this, a large random sample of body count figures was examined and the frequency with which the last digit was a 0 or a 5 was recorded. Psychologists have shown that people making up their own €˜€˜random€™€™ numbers will use these digits less often than random chance would suggest (i.e. 103 sounds like a more €˜€˜real€™€™ count than 100). If the data were authentic counts, the proportion of numbers ending in 0 or 5 should be about 0.20. Do these data show evidence of fabrication?

We have learned a lot of methods in this course, some of which are given below. State which statistical method would be most appropriate for the given question or situation.

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Interval for a Proportion Interval for a Mean Interval for Difference in Proportions Interval for Difference in Means Interval for Correlation Test for a Proportion Test for a Mean Test for Difference in Proportions Test for Difference in Means Test for Correlation Chi-Square Goodness of Fit Chi-Square Test for Association ANOVA for Difference in Means Simple Linear Regression Multiple Regression