I'm studying to be an auditor (CIA exam), but I do not have a statistics background and I'm very confused regarding the difference between confidence intervals and precision, then how they relate to confidence level. I know that as a confidence level is increased (eg: 90% to 95%), the confidence interval widens. In my exam material, it states, "in terms of a stated confidence level, precision is the range into which an estimate of population characteristic is expected to fall. Based on a random sample, it is estimated that 4%, plus or minus 2%, of a firm's invoices contain errors. The plus or minus 2% is the estimate's precision". This sounds almost exactly like what a confidence interval is to me, yet the terms are used separately and seem to have different relationships with the confidence level, "when a confidence level is changed from 95% to 99% and no change in sample standard deviation takes place, the sample size would be larger but achieved precision would not change".
Thank you so much!