Confused about why one relationship is said to be greater than another? You are not alone. Many students find this concept strange at first. For example, which of the following is a greater change?
| Original Value | New Value | Difference |
| 2 | 4 | 4 - 2 = 2 |
| 100 | 110 | 110 - 100 = 10 |
If you look at the difference column, it looks like the second row – a change from 100 to 110 – is bigger. But what if we calculated the change as a percentage increase. To do this, take the difference, and divide it by the original value (multiply by 100 to make it a percentage).
| Original Value | New Value | Difference | Percentage Increase |
| 2 | 4 | 4 - 2 = 2 | (4-2)/2 x 100 = 200 % |
| 100 | 110 | 110 - 100 = 10 | (100-110)/100 x 100 = 10% |
Look at the percentage increase column. Obviously, based on percentage change, the change for the first row – a change from 2 to 4 – is much larger.
The percentage change represents the magnitude of change, or how many times larger one number is than another. When dealing with changes, it is much more meaningful to compare the magnitude of change, rather than the actual change.
So when comparing values to see which is the most constant, do the following:
Multiply this answer by 100 and you will have the percentage change.