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Often a high confidence level (95 or 99%), means that your interval must be very large (high margin of error). Ultimately, we would like to create a confidence interval with a high confidence level and very small margin of error. How can we control that???.
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Often a high confidence level (95 or 99%), means that your interval must be very large (high margin of error). Ultimately, we would like to create a confidence interval with a high confidence level and very small margin of error. How can we control that??? Make the z* value smaller that causes you to accept a lower confidence level. Make the s value smaller this does make it easier to get a more accurate m, but is difficult to do Make the n (sample size) larger dividing by a larger number makes smaller and in turn the margin of error smaller Best Option!
So how do we find the desired sample size? Let m = the desired margin of error So, Now solve for n. Pg 640 #20b Divide by 2.575 Multiply by and then divide by 1.9417 Square both sides to clear the radical The sample size must be at least 2653 people