Histograms Type of graph based on frequency distribution. Width of each bar indicates upper and lower real limits of the score or class interval, so there is no gap between bars. Frequency Polygon Type of graph based on frequency distribution. Each adjacent point is connected with a line. Cumulative Frequency Polygon Type of graph based on a cumulative frequency distribution.
Cumulative frequency associated with each score or interval is indicated by a point.
Each adjacent point is connected with a line. Mean is the point where algebraic deviations from it sum to 0. To obtain m, we add all the population scores and divide by the N in population. To obtain x, we add all the sample scores and divide by the N in the sample. Remember with one sample, the mean is the unbiased estimate of the population mean.