How do I calculate percentage error for ph values (measured using universal indicator)?

So I know that normally when you calculate percent error you divide uncertainty by the value...



but since pH is a log scale how do I do an error analysis



Eg. With pH paper (universal indicator) I measured pH=3How do I calculate percentage error for ph values (measured using universal indicator)?
it's the same way. if the measured pH = 3.0 卤0.15, then you have (卤0.15/3) x 100 = 卤5%



also note that the uncertainty is related to each individual measurement, and that sometimes, uncertainty is greater at one end of a non-linear scale than it is at the other end. it is not unusual to see error bars on graphs that have a lot more uncertainty in one than the other of their bounds.



in general, ultimate uncertainty of a complex, nonlinear formula in m variables can be calculated in 2^m trials, where each variable is substituted with its maximum value or its minimum value.