The mode is the most common score of all the scores in a sample. The mean is the arithmetic average of a group of scores. It is calculated by summing all the scores in a data set and then dividing this sum by the total number of scores. A bimodal distribution has two modes, or most common scores. Central tendency refers to the descriptive statistic that best represents the center of a data set, the particular value that all the other data seem to be gathering around. A unimodal distribution has one mode, or most common score. The median is the middle score of all the scores in a sample when the scores are arranged in ascending order. If there is no single middle score, the median is the mean of the two middle scores. A statistic is a number based on a sample taken from a population; statistics are usually symbolized by Latin letters. A multimodal distribution has more than two modes, or most common scores. A parameter is a number based on the whole population; parameters are usually symbolized by Greek letters. |