Why are the Styku measurements different than my tape measure measurements?

Styku's measurements are more accurate than tape measurements taken by hand, and more repeatable.

All methods of measuring have error. Styku's circumferences are precise and reliable.

We can measure the error of a measurement by comparing it to a 'ground truth' value that has a lower margin of error than the measurement we're comparing it to.

To determine the error margin of Styku's measurements, we compare the standard deviation between three or more samples of the same measurement to the average of those samples. This gives us a "percent error" value. In the torso, the expected margin of error for a Styku circumference measurement is +- 0.5% error, or around half of one percent of the measurement value.

To put it another way, If Styku measures a Waist at 40 inches, repeated scans of the same person around the same time will be within 0.2 inches of the original value of 40 inches (0.5% of 40 is 0.2). The precision or repeatability of the Styku measurement is within 0.2 inches.

But why doesn't Styku match my tape measurements?

The simple answer as to why Styku's measurements may be different from your tape measure measurements is that a) Styku measures differently than you do, and b) your measurement has a larger margin of error than Styku's measurement.

For example : Ask 3 people to measure 1 person's abdominal waist. You will get 3 different values, because we haven't defined where to measure on the person's body.

If we set a standard measurement location, we'd get a closer spread of values, but it still won't be the same for all 3 samples, because each person will hold the tape differently on the subject's body - tighter, looser, higher, lower.

The average error for tape measurements is greater than Styku's margin of error. In our tests, the difference between measurements taken by different people of the same person can be greater than 1 inch.

As a result of these factors, it's likely that Styku's measurement and your tape measurement won't be dead on every time. But that's ok!

When we're tracking change in someone's shape and size, what matters is repeatability.

You can only track change in a measurement if the amount of change is greater than the margin of error. If the error margin is relatively low, then you can be confident that the change you're seeing is real and not just "noise".

Styku's measurement precision is better than tape measurements, so it's a better tool for tracking change.

Despite what the value is, if the repeatability of the measurement is high - meaning having a consistent position, and having a low margin of error - you will be successful in tracking progress for your customers.

At the end of the day, what matters more is not that the Waist measurement is 40 inches, but that it has gone down by 3 inches from the last scan!