Bootstrap Confidence Intervals (CIs)
Sort 500 resampled values and read off two percentiles. That is the whole method, and it works for statistics that have no convenient formula.
Sort 500 resampled values and read off two percentiles. That is the whole method, and it works for statistics that have no convenient formula.
A margin of error needs a confidence level to exist. Quote one without it and you are off by the multiplier — about a factor of two at 95%.
Enumerated exactly, not simulated: the Wald interval delivers 0.8775 where it promises 0.95.
Split the same outcomes by what was observed and coverage runs from 1.0000 to 0.5979.
Observed power and the p-value are two readings of the same statistic. A near-miss result will always come back as low power.
95% is a property of the method, not of the interval in front of you. A higher level targets greater coverage across samples and usually widens the interval; it does not assign a posterior probability to the observed interval.
The textbook proportion interval can put its lower bound below zero. Inverting the test instead gives bounds that stay inside the range.
The bootstrap gives you a sampling distribution for statistics that have no convenient formula. What it cannot give you is a fix for a biased sample.
95% describes the procedure across repeated samples, not your confidence in this particular interval. The distinction changes how you report it.
A noninferiority test asks whether a new option is worse than the old one by no more than a margin chosen in advance, and it passes only when the confidence interval’s lower bound clears that margin.