I've got a set of figures that I want to track the percentage change for and then throw away the figures and just hold the calculate percentage movements.
Easy so far!
Now the trickier bit.. I want to then be able to re-base my percentage changes against any of the figures in my list.
So for example:
Figures: 1 2 4 4 8 16 6 3 5 2
Percentage Increase: 0 100 300 300 700 1500 500 200 400 100
Re-based figures on '8': 8 16 6 3 5 2
Percentage Increase: 0 100 -25 -62.5 -37.5 -75
My question, is how can I work out from the initial percentages alone, what the percentage changes should be following my re-base?
Best Answer
If I understand the question correctly, you just need to add $100$ to each of the percentage increases, then calculate the percentage increase of these numbers. In your example, we'd have $$\matrix{\text{Figures} &800 &1600 &600 &300 &500 &200\\ \text{Pct. Increase} &0 &100 &-25 &-62.5 &-37.5 &-75}$$