A) Increase the pilot sample standard deviation and simultaneously decrease the

Question

A) Increase the pilot sample standard deviation and simultaneously decrease the required confidence level:
      ---Select---  Increase Decrease Remain the same Cannot be determined

B) Decrease the required margin of error and increase the confidence level:
      ---Select---  Increase Decrease Remain the same Cannot be determined

C) Increase the population size from 6 million to 16 million and increase the pilot study sample average:
      ---Select---  Increase Decrease Remain the same Cannot be determined

D) Increase the population size from 6 million to 16 million and increase the required margin of error:
      ---Select---  Increase Decrease Remain the same Cannot be determined

E) Increase the required margin of error and, simultaneously, increase the confidence level :
      ---Select---  Increase Decrease Remain the same Cannot be determined
Consider that a pilot study has been done for the purposes of estimating the sample size required in order to obtain a CI for a population average. For each of the following changes choose whether the effect on the required sample size would be an increase, a decrease, remain the same, or indeterminable.

Explanation / Answer

a)

Note that      
      
n = z(alpha/2)^2 s^2 / E^2      

Hence, it depends on how much we change each variable. CANNOT BE DETERMINED. [ANSWER]

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b)

From the equation above, then INCREASE. [ANSWER]

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c)

Population size does not matter if it's that big, and sample average does not affect the sample size.

REMAIN THE SAME. [ANSWER]

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d)

Greater margin of error means smaller sample size.

ANSWER: DECREASE

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E)

It depends on how we change both variables. So,

IT CANNOT BE DETERMINED. [ANSWER]

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