The Open Door Web Site
ALL ABOUT GRAPHS
Graphs, why use them?
This can be best demonstrated by means of an example.
The table opposite shows a typical response of pulse rate, measured at one minute intervals, before and after a period of exercise. Notice the table contains pure dimensionless numbers (e.g. 4 and not 4 min). The column headings contain the relevant information including the units.
Just by looking at the table you can see the pulse has increased after the 10 minute run and then returns to normal after about 10 minutes, as you might expect. Plotting a curve of these data, however, reveals an interesting phenomenon. The return to normal is not a smooth one. The pulse rate passes below its resting value several times. This overshoot is normal and it illustrates that the heart beat is under negative feedback control.
Pulse Rate of a male 16 year old before and after a 10 minute run.
All this interpretation of data could have been determined from the list of readings in the table but it is a lot easier to see what is going on when the results are displayed in the form of a graph.
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