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What “95% confidence” actually means, and how the interval changes if you raise or lower that level.
The confidence level does not measure how sure you are of the specific result you got. It measures something else: if you repeated the study many times with the same design, that percentage of the calculated intervals would contain the universe’s true value.
Going from 95% to 99% does not make the study better: it makes the interval wider, because being wrong less often means betting on a bigger range. That is why 95% is the industry standard — it is the point where the interval is still useful for deciding.
Tell us what decision you are facing and we will tell you which study answers it.