When we are in the lab, I know how to get the uncertainty for a measurement I make directly or indirectly, but what would be the uncertainty in measurements that are directly given to us? For instance, circuit lengths in connectors are represented by different codes (e.g. SF38 is 4 cm long).
Ideally it would be +/- 0.5 of the last decimal place.
So if the maker says a part is 4cm then it is between 4.5 and 3.5 cm
If they say 4.0cm then it should be 4.0 +/- 0.05 (between 4.05 and 3.95 cm)
If the accuracy matters then you would have to measure a sample of the parts and get an idea of the distribution of actual lengths