Do you guys weigh your grains before throwing them in the pot? I have a triple beam balance good down to 0.1 g, and I measured as accurately as possible all the 1 lb and 1/2 lb bags from Midwest that I was putting into the brew. Guess what...they were ALL under weight. They were only about 95% of their stated mass. Even though this is a small sample of bags (4 bags), I'm starting to think this might be consistent.
One thing I could do is keep measuring all my bags and get the sample mean and standard deviation. If the mean is not 100% and the standard deviation gives a 90 to 95% confidence interval that does not include 100%, then either my balance is wrong (which I doubt), or they are under-filling either by mistake or on purpose. It's perhaps not so bad when you do large batches, but for the small batches I make, it makes a lot of difference, and I don't like tweaking the recipe 20 minutes before I mash in.
One thing I could do is keep measuring all my bags and get the sample mean and standard deviation. If the mean is not 100% and the standard deviation gives a 90 to 95% confidence interval that does not include 100%, then either my balance is wrong (which I doubt), or they are under-filling either by mistake or on purpose. It's perhaps not so bad when you do large batches, but for the small batches I make, it makes a lot of difference, and I don't like tweaking the recipe 20 minutes before I mash in.