Qnt 561 confidence interval calculate confidence interval, sample
Confidence interval: A confidence interval is a range of values that is likely to contain the population parameter with a certain level of confidence. It is used to estimate the population mean or proportion from a sample statistic with an associated level of confidence. The formula used to calculate a confidence interval for a population proportion p is:
CI = p ± z*sqrt(p*(1-p)/n)
where n represents the sample size, and z represents the critical value from the standard normal distribution (Z-score).
Sample size estimation for proportion: Sample size estimation for proportions involves calculating the necessary sample size in order to be able to estimate an unknown population proportion within a desired degree of accuracy. To do this, one must consider three factors: The degree of accuracy desired, the maximum margin of error allowed, and the assumed value of p (the estimated population proportion). Generally speaking, if all other variables are fixed, then larger samples will result in more precise estimates. The formula used to calculate the required sample size given these factors is as follows:
n = [(z^2)*p*(1-p)]/e^2 where z represents the critical Z-score based on your chosen level of significance (usually 95%) and e represents your maximum acceptable margin of error.