In Part I of the Statistics Series, which appeared in Journal of Orthodontics, Vol. 27, No. 3 September 2000, an error was printed on p. 270, second column. Unfortunately, in Vol. 27, No. 4, 2000, p. 340, an incorrect Erratum was printed!
Oxford University Press and the Editors apologize to the author and subscribers for this error. The corrected passage is shown here.
Usually, a 95 per cent confidence interval (CI) is calculated. This is defined as x̄ ± t × SE. SE denotes the standard error of the mean, which is SD/√n, here 124/√20 = 22•6. It expresses the precision of the sample mean. The multiplier, t, is approximately 2 for a 95 per cent CI.