STATISTICAL TECHNIQUES AND TOOLS
CONFIDENCE INTERVALS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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1141
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3267
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1068
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1067
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Detailed explanation-1: -To calculate the confidence interval, we must find p′, q′. p′ = 0.842 is the sample proportion; this is the point estimate of the population proportion. Since the requested confidence level is CL = 0.95, then = 1 – CL = 1 – 0.95 = 0.05 ( 2 ) ( 2 ) = 0.025.
Detailed explanation-2: -For a margin of error of 5% and confidence level 95% you will need 356 respondents in total (see also our sample size calculator, spread proportionally across the schools. This is when you want to draw conclusions for your population in general.
Detailed explanation-3: -In the large-sample case, a 95% confidence interval estimate for the population mean is given by x̄ ± 1.96/ √n. When the population standard deviation, , is unknown, the sample standard deviation is used to estimate in the confidence interval formula.