Interpret Data: Interpret Line Graphs . Line graphs are used represent continuous data which is data where there are values between the values chosen to be represented on the graph. Continuous data are measurements like time. . Line graphs allow change in data over time to be visualised and the relationship between the two variables are represented as changes in the line. Line graphs can also be misinterpreted if they are thought to be a picture rather than a data representation e.g. of climbing