ITEE ITEE-1 | Page 37

●Line chart A “line chart” typically shows a numerical value along one axis an elapsed time along the other, with a line connecting points plotted at each time marker, giving this graph its name. It is used to represent trends over time, as with changes during the course of a year. Minimum temperature by region (2009) ℃ 25 20 15 Region A Region B 10 Region C 5 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Reference ●Regression analysis “Regression analysis” expresses a correlation between two kinds of data that are plotted on a scatter diagram, using a straight line to show the relationship. If the two kinds of data are “x” and “y,” then the linear regression can be expressed as “y=ax+b.” In this case, “a” is the “slope” of the linear regression, and “b” is the “y-intercept.” For example, in this graph, if the annual average temperatures can be predicted, beverage sales can also be predicted, which would help determine quantities of products to order. A linear regression is a straight line with the shortest distance to each point, which is calculated using the “least-squares method.” Least-squares method y y=ax+b Cold-beverage sales profit The “least-squares method” draws a straight line that has the smallest total value for the squares of the distances between plotted points and the regressed line. Linear regression x Temperature 31