When Styku shows progress metrics, we use two values - net change and percent change. Read below to learn the difference and why for challenges or competitions, percent change is the better metric to use.
The Styku Progress Report and Challenge Report illustrate change in a body measurement in a few ways, including a Net Change value ("Lost 8 lbs.") and a Percent Change value ("5.3% loss").
It's important to know the difference, and what these numbers mean.
Net Change vs Percent Change - How they are calculated
Net Change is pretty straightforward - it's the difference between the first and last scan values for that measurement.
If, in your first scan, you had a weight of 150 lbs., and in your last scan your weight was 140 lbs., you will have a Net Change of 10 lbs. (150-140 = 10).
Percent Change is the percentage of the total value that the change represents, and is calculated using this formula:
(ending value - starting value) / starting value * 100
To use the above example again, if we started with a weight of 150 lbs., and we ended with a weight of 140 lbs.:
(140-150)/150 * 100
(-10)/150 * 100
0.0667 * 100
So that 10 lb. net difference between our first and last scan is a 6.67% change from 150 lbs., our starting value.
Why Percent Change is a better value for determining challenge winners
To illustrate why this is an important distinction, let's use weight change again, but this time let's compare two different people's weight change.
John weighed in at 350 lbs. in his first scan, and lost 10 lbs during our challenge.
Nick weighed in at 120 lbs in his first scan, and also lost 10 lbs during the challenge.
The Net Change values for both men is the same - both of them lost 10 lbs.
However, if we look at the Percent Change value, you'll see a big difference:
John: (340-350) / 350 * 100 = 2.85% of total weight
Nick: (110-120) / 350 * 100 = 8.33% of total weight
If, to determine our challenge winner, we went with Net Change, we would assume that John and Nick tied - both lost the same amount.
However, looking at Percent Change, it's clear that it's a bigger deal and more of an achievement to lose 10 lbs if you weigh 120 lbs, vs to lose 10 lbs if you're 350 lbs. The Percent Change value shows this effort, while the Net Change value does not.
Bottom line, when you want to "level the playing field" for participants in a challenge, use Percent Change rather than Net Change for the measurements you are comparing in the challenge.