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frequency polygon uses line segments connected to points located directly above class midpoint values relative frequency polygon variation of the basic frequency polygon. uses relative frequencies (proportions or percentages) for vertical scale. to compare two data sets, graph to relative frequency polygons on same axes Ogive useful for determining the number of values below some particular value. it's a line graph that depicts cumulative frequencies. uses class boundaries along the horizontal scale (X) and cumulative frequencies along vertical scale (Y) dot plot consists of a graph in which each data value is plotted as a point along a scale of values. dots representing equal values are stacked stem plots represents quantitative data by separating each value into two parts: the stem (the leftmost digit) and the leaf ( the rightmost digit) pie chart a graph that depicts qualitative data as slices of a circle in which the size of each slice is proportional to the frequency count for the category nonzero axis some graphs are misleading because on or both of the axes begin at a value other than zero, so differences are exaggerated pictographs drawings of objects, are often misleading because they can create false impressions that distort differences measure of center a value at the center or middle of a data set: several way to determine the center; different definitions like mean, median, mode, and mid-range mean an average; arithmetic mean of a set of data = the measure of center found by adding the data values and dividing the total by the number of data values sample size (n); the number of data values mean formula the sum of all data values/ the number of data values median a data set = the MOC that is the middle value when the original data values are arranged in order of increasing/decreasing magnitude median rules 1. if data values = odd, then median is in exact middle of list 2. if data values = even, median is found by computing mean of two middle numbers mode data set = the value that occurs with the greatest frequency bimodal two data values occur with the same greatest frequency multimodal when more than two data values occur with same greatest frequency; each one is a mode no mode when no data value is repeated midrange data set = the MOC that is the value midway between maximum and minimum values in the original data set; found by adding maximum data value to minimum data value / 2 midrange formula maximum data value + minimum data value / 2 round-off rule carry one more decimal place than is present in original set of values; because values of the mode are the same as some of the original data values, they can be left as is without any rounding