In a recent experiment, I have found the viscosity of glycerol by measuring the time it took for steel balls of measured density and radius to fall a certain distance in the liquid.
Now, I need to compare this data with a theoretical value given by a certain graph of glycerol viscosity by temperature. I have measured the temperature in the lab and know the average temperature throughout the experiment and its error.
In order to compare the values, I need to know how to properly take data from a given (printed) graph and calculate the error of the value.
I don't really know how to approach it, and it is not something that has been explained previously (nor did I find much data online about lab statistics).
A possible method I thought about is to add the resolution errors of the axes and add the error in measured temperature, but that would give an answer with inconsistent units.