SOLUTION: A poll for the presidential campaign samples 491 potential voters in June. A primary purpose of the poll was to obtain an estimate of the proportion of potential voters who favored

Question 521469: A poll for the presidential campaign samples 491 potential voters in June. A primary purpose of the poll was to obtain an estimate of the proportion of potential voters who favored each candidate. Assume a planning value of p* = 0.50 and a 95% confidence level.
a. For p* = 0.50, what was the planned margin of error for the June poll? (Without calculation process, no credit)
b. closer to the November election, better precision and smaller margins of error are desired. Assume the following margins of error are requested for surveys to be conducted during the presidential campaign. Compute the recommended samples size for each survey. (Without calculation process, no credit)
Survey Margin of Error
September 0.04
October 0.03
Early November 0.02
Pre-Election Day 0.01

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A poll for the presidential campaign samples 491 potential voters in June. A primary purpose of the poll was to obtain an estimate of the proportion of potential voters who favored each candidate.
Assume a planning value of p* = 0.50 and a 95% confidence level.
a. For p* = 0.50, what was the planned margin of error for the June poll?
ME = z*sqrt(pq/n)
ME = 1.96*sqrt[0.5*0.5/491] = 0.0442
(Without calculation process, no credit)
b. closer to the November election, better precision and smaller margins of error are desired. Assume the following margins of error are requested for surveys to be conducted during the presidential campaign. Compute the recommended samples size for each survey. (Without calculation process, no credit)
Survey Margin of Error
September 0.04
n = [z/ME]^2*pq
n = [1.96/0.04]^2*0.5^2
-----------------------------
Comment: Same pattern for Oct, Nov, pre-elect.
Just change to a different ME value
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Cheers,
Stan H.
===================
October 0.03
Early November 0.02
Pre-Election Day 0.01

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