Stata tip 103: Expressing confidence with gradations

摘要

Researchers often express the uncertainty associated with a parameter estimate μ by plotting the 95% confidence interval (CI) around the statistic. The meaning of these intervals is that in the long run, 95% of the intervals formed in this way will include the fixed but unknown parameter of interest μ. It is also true, though we often neglect to mention it, that "the unknown μ is more often captured near the center of an interval than near the lower or upper limit, or end-point, of an interval" (Cumming 2007, 90).