Re: 4/20 Merlin AMPS/380,+5/404,PMPS/407,+4/146,+5/107,+6/20
Remember meter variance of +/- 20%.
You can narrow that range by doing 2 tests and using the overlap area of both.
Example ranges
100 -> 80 to 120 - not different from 125
125 -> 100 to 150 - not different from 100, nor 150 due to range overlap
150 -> 120 to 180 - not different from 125, nor 175 due to range overlap
175 -> 140 to 210 - not different from 160, nor 200 due to range overlap
200 -> 160 to 240 - not different from 175 due to range overlap
Notice how the range of possible numbers widens as the test values increase.
Once you're up high enough, the actual differences are irrelevant. High is high and you'll want to figure out your options.
Low numbers are where you want to be careful due to the risks of hypoglycemia.