# Sample Size

Having been retained by the National Native American Political Party to conduct a poll of residents of Muscogee, Oklahoma, you have worked diligently on completing interviews with residents of that town for three weeks. Your budget of $10,000 is expended. You have completed 270 interviews.

(A) If you promised to deliver a survey that is accurate plus minus 5% at a confidence level of 90%, can you say, using a conservative basis for estimation, that you have reached your objective? (Assume normally distributed data.) If your answer is yes, justify. If no, is there any way of adjusting your procedure to meet the requirement?

(B) If the data were oriented toward simply determining whether the people of Muscogee would or would not vote for a bond issue, how would your analysis change? (Assume equal likelihood of yes versus no).

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#### Solution Preview

(A) If you promised to deliver a survey that is accurate plus minus 5% at a confidence level of 90%, can you say, using a conservative basis for estimation, that you have reached your objective? (Assume normally distributed data.) If your answer is yes, justify. If no, is there any way of adjusting your procedure to meet the requirement?

No of tails= 2

This is a 2 tailed test for normal distribution

as we are checking the accuracy of plus minus 5%

sp=standard error of proportion=square root of (pq/n)

(The maximum value of standard error of proportion for any given value of n is when ...

#### Solution Summary

Calculates accuracy for a given sample size and sample size for a given level of accuracy.