There’s a lot of ways to articulate the amount of change between two or more numbers. Very often an explanation can be interpreted in more than one way, and/or hide important elements of truly how much something has changed. Unfortunately there is no one right answer, but we do think there is an answer - and it’s to use all metrics of change, all of the time. In doubt, better to give too much information than less.
Pros vs. Cons
There's more than just one "pro" and "con" for each change metric, but below represents a simplified perspective:
Below is a table that shows exactly how to calculate each change metric for percentages (% to %) and real numbers (# to #). Take note that Basis Point and Percentage Point apply solely to percentages, and that dealing with percentages are always a bit easier when converted to decimal form (at least we think so):
% to % Examples
Below are a few examples showing the results for measuring change between percentages. Each percentage is first converted to decimal form. The first and last row show the entire formula.
# to # Examples
Below are a few examples showing the results for measuring change between real numbers. The first and last row show the entire formula.