A normal curve is a specific bell-shaped curve that is unimodal, symmetric, and defined mathematically. The central limit theorem refers to how a distribution of sample means is a more normal distribution than a distribution of scores, even when the population distribution is not normal. A distribution of means is a distribution composed of many means that are calculated from all possible samples of a given size, all taken from the same population. The z distribution is a normal distribution of standardized scores. A z score is the number of standard deviations a particular score is from the mean. The standard normal distribution is a normal distribution of z scores. Standardization is a way to convert individual scores from different normal distributions to a shared normal distribution with a known mean, standard deviation, and percentiles. Standard error is the name for the standard deviation of a distribution of means. |