Reading an Uncertain Measurement
A short physics note on uncertainty, significant figures, and what an experimental result can honestly claim.
Demo content. This sample note demonstrates the Physics article style. It is not an active post by Russell.
A measurement is not simply a number. It is a number accompanied by a statement about how precisely the experiment could determine it.
#The interval matters
Writing a length as says that the best estimate is 12.4 cm and that values within the stated uncertainty remain plausible. The uncertainty is part of the result, not an optional footnote.
#Precision is not accuracy
- Precision describes how tightly repeated measurements agree.
- Accuracy describes how close a result is to the underlying value.
An instrument can give remarkably consistent readings while being systematically miscalibrated. Repetition reduces random uncertainty, but it does not automatically repair systematic error.
#A useful reporting habit
Match the decimal place of the measured value to the decimal place of its uncertainty. Reporting advertises information the experiment did not establish.
The honest conclusion is rarely the longest number. It is the number whose precision matches the evidence.