### Percent of Total Change

This aggregate should be understood
as “Change in (Percent of Total)”, not as “Percent of (Total Change)”.
It is the result of calculating Percent of Total on two different
columns, and then calculating the difference between them. The result
is presented as the difference in *percentage units*, n.b.

This aggregate is typically used for comparing Percent of Total based on current values, to Percent of Total based on previous values. Therefore, the column specified as “Previous Values Column” in the settings, should be the column containing previous values.

The aggregate value is calculated as a ratio between 0 and 1 and will be presented as a percentage value by applying a percent format string in the aggregation settings. Optionally, you can emphasize that the value is a percentage units by customizing the format unit, for example: 0.00%'-units'.

**Sample**

ID |
Current value |
Previous value |
Total of current |
Total of previous |
Percent of Total (current) |
Percent of Total (previous) |
Percent of Total Change |

A |
25 |
25 |
100 |
125 |
0.25 |
0.20 |
+0.05 |

B |
45 |
65 |
100 |
125 |
0.45 |
0.52 |
-0.07 |

C |
30 |
35 |
100 |
125 |
0.30 |
0.28 |
+0.02 |