Originally Posted by
cyccommute
I was reviewing this chart and discovered that it isn’t that clear. It does show the ±20% values but the values for the actual error is far lower. None of the measurements on the chart even approach that ±20%. Dividing the standard deviation by the mean, the value in this 7%. They could stand a lesson in significant figures, however. 17.93 and 23.63 reading on the tension meter? Really? The Park tension meter would be questionable past whole number values.
I think all that means is that in that particular example, the builder was able to come much closer than 20%. Of course you're going to get it as close as possible, and the 20% variance is just where it throws a warning.
You're probably right that the Park Tool is not accurate out to two decimal places.