Some things take persistence. Determining the accuracy of my $2.99 thrift-store kitchen scale, it seems, is one of them.
The plan was simple: Make a test skein of my thrifted wool. Measure the yardage. Weigh it at home. Weigh it at the post office. Calculate the difference and note it as a statistical variance on my scale.
Test skein = 46.5 yds
Weight on Kitchen Scale = 10 g
Weight on Post Office Scale = 0.3 oz (8.50485 g)
5.4675 yds/g, which is more than the 4.65 yds/g I thought.
Difference = 1.5 g — more than 10%
It is a statistically significant amount: If I were calculating yardage based upon weight, I would have been off by 6.975 yds just on this little test skein. Potentially 177.9 yds on the entire 9 ounces recycled.
I decided that I can't decide yet whether this is acceptable. I need more research. This time, I'll take the entire batch to the digital scale to find out if the variance is the same with a larger weight.