Any normal population’s distribution approximates a normal distribution. This means that majority of those that comprise the population are situated in the middle portion of the distribution while a minority are evenly distributed to either side of the middle portion. Many variables are deemed to be normally or approximately normally distributed, e.g., height, weight, IQ, etc. Hence, in a given population, majority of people are of average height while a lesser numbers are either extremely high (right side of the middle portion) or extremely short (left side of the middle portion). In relation to this, one statistics professor commented “God so loves the average man that He made so many of them.” Can you imagine a world where majority are morons or geniuses?
When the value of a variable with a normal distribution is presented in a graph, what results is a bell-shaped curve popularly known as the normal curve. For purposes of statistical manipulation, a minimum sample of 30 (n=30) is required as such a number or larger can be relied upon to yield an approximate normal distribution of means. For any variable, as the sample size increases, the more the distribution approximates a normal distribution.
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