Question

Use minitab to solve the following:

3. Should professional athletes be tested for drugs? Reporting on this question, the Orlando Sentinel (October 31, 1985) noted that Donald Fehr, executive director of the Major League Baseball Players’ Association, “criticized mandatory testing as being unnecessary.” The public did not agree. A Washington Post-ABC News survey found that 73% of 1506 people interviewed favored drug test for professional athletes and 68% agreed that professional athletes discovered to be using should be banned or suspended from professional sports on the first offense.

a) Find a 96% confidence interval for the proportion/percentage of the public that favors drug tests for professional athletes.

b.)Upon what assumption is your confidence interval in parts a) based?

Answer 1

Here the proportion of public that favors drug tests for professional athletes = 0.73

total people surveyed = 1506

standard error of proportion = sqrt (p * (1 - p)/n) = sqrt [0.73 * 0.27/1506] = 0.01144

here 96% confidence interval = samle proportion +- margin of error

margin of errro = critical test statisic * standard error of proportion

critical test statisic for 96% confidence interval = 2.054

margin of error = 2.054 * 0.01144 = 0.0235

96% confidence interval = 0.73 + 0.0235 = (0.7065, 0.7535)

(b)

Here assumptons are

(i) sample taken is a simple random sample.

(ii) THere is no bias in the sampling.

(iii) The sample values must be independent of each other. This means that the occurrence of one event has no influence on the next event.

(iv) sample size, n, should be no more than 10% of the population.