Otherwise known as the probability of Type I error. The measured probability of a finding occurring, i.e. rejecting the null hypothesis, by chance alone given that the null hypothesis is actually true. The probability of detecting an effect in the treatment vs. control group if a difference actually exists. Must also specify the size of the difference. Mistakenly rejecting the null hypothesis when it is actually true.
Alpha is determined before the study begins.
False positive conclusion. False negative conclusion. A measure of variability. The standard error of the mean quantifies how accurately the true population mean is known. A measure of the variability of the mean of the sample as an estimate of the true value of the population mean.