Interpreting Graphs 5

A scatter graph is used to find out whether there is a relationship between two variables, for example body mass and heart rate in different mammals.Each individual is plotted as one point. A line of best fit may be drawn through the middle of the points, with roughly equal numbers of points on each side.If the points slope upwards there is a positive correlation. If they slope downwards there is a negative correlation. If there is no pattern there is no correlation.The closer the points are to the line of best fit, the stronger the correlation.Points that lie far from the general pattern are anomalous and should be identified when describing the data.A scatter graph can show a correlation, but it cannot show that one variable causes the change in the other. A statistical test is needed to find whether a correlation is significant.