Recording and Graphing Data

Graphing Data

Graphing data is a pictorial method of representing data that can be used when there is a relationship between one or more groups of data from an experiment. In many instances the values measured for one quantity depend on the value of another. The benefits of graphing data and good graphing techniques are shown in the following example.

Suppose that an experiment was performed during a chemistry test. Both the number of hours each student studied for the test and the grade they earned were recorded. The following data was obtained.

Hours Studied Grade Received Hours Studied Grade Received
1.0 35 3.3 70
3.0 55 4.0 80
2.3 42 2.0 39
6.0 94 3.0 50
1.5 36 0.0 34
7.0 96 5.5 95
5.0 90 4.3 83

While neatly organized, any trend between the number of hours studied by the students and the grade they earned is difficult to pick out. Graphing the data makes the trend more obvious.

The graph clearly shows that an increase is study time results in a higher grade. However, it also shows that studying less than two hours does little to help the grade received. Likewise, studying more than five hours will not increase the grade significantly either. Obviously, this is a very small sample of data and we should be very careful about any conclusions we draw.

Besides showing the relationship between study time and grade received for an imaginary chemistry class, the graph demonstrates many good graphing practices.