Once the sample has been selected and the data has been collected, you have to calculate estimates for then population parameters. You can use the tools below the compute estimates for a population percentage and a population mean. To be able to do this, you must first enter the data.
Not only an estimate is computed, but also a confidence interval. This interval contains the true ppopulation level with a high probability. This high probability is called the confidence interval.
You have two options for the confidence level: 95% or 99%. Note that is relation between the confidence level of the confidence interval and the precision of the estimate:
 A choice for a higher confidence level (99%) will lead to a wider confidence interval, and thus to a less precise estimate.
 A choice for a lower confidence level (95%) will lead to a smaller confidence interval, and thus to a more precise estimate.
So you either draw a very precise conclusion with a lower level of confidence, or a less precision conclusion with a higher level of confidence.
The first step is to select the confidence level. There are two options: 95% or 99%:
