ABSTRACT
The normal distribution, sometimes called the normal curve or bell-shaped curve, is a graphical display of a set of scores whose distribution approximates a bell curve. It is a distribution that occurs naturally in many situations, such as people's height, weight, IQ scores, academic grades, and salaries. Moreover, in a symmetrical bell curve distribution, the mean, median, and mode are all equal. It is possible to calculate any area contained under the standard normal (bell-shaped) distribution from its mean (µ) and standard deviation (s). A standard score or z score depicts the number of standard deviations from (above or below) the distribution's mean. In addition, z scores allow comparison between scores in different distributions, even when the units of measurement in the distributions are different. This ability to make meaningful comparisons between scores with different distributions is especially beneficial to educators because it allows comparisons to be made between tests with different distribution characteristics, that is, mean and standard deviation.
