Title: Confidence Intervals and Levels | Educational Research Basics by Del Siegle
Headings: Confidence Intervals and Levels
Confidence Intervals and Levels
Content: the 99% confidence level means you can be 99% certain. Most researchers work for a 95% confidence level. When you put the confidence level and the confidence interval together, you can say that you are 95% sure that the true percentage of the population is between 43% and 51%. Factors that Affect Confidence Intervals
The confidence interval is based on the margin of error. There are three factors that determine the size of the confidence interval for a given confidence level. These are: sample size, percentage and population size. Sample Size
The larger your sample, the more sure you can be that their answers truly reflect the population. This indicates that for a given confidence level, the larger your sample size, the smaller your confidence interval. However, the relationship is not linear (i.e., doubling the sample size does not halve the confidence interval).