Confidence Intervals - Conditions When calculating confidence intervals it is important to pay close attention to sample size and whether or not you have the true value of sigma. http://www2.cedarcrest.edu/academic/bio/hale/biostat/session17links/conintervalcon.html
Type I and Type II error. Type I error occurs when one rejects the null hypothesis when it is true and its denoted by alpha (false positive). Type II error occurs when accepts the null hypothesis when it is false and its denoted by beta (false negative).