Dear
I am interested in the values of the parameters sigma a, sigma b, and sigma c in a 1D network (Leveling measurements). How do sigma b and sigma c depend on the distance between points? For example, if the leveling distances are between 100 and 200 meters, what should be the value of sigma b? In one of your previous responses, I found that sigma b is actually the accuracy of the instrument we use for leveling. For instance, if the instrument’s accuracy is 1mm/km, then sigma b is 1. Is this correct?

I am most interested in the value of the sigma a parameter. What should its value be and what does it depend on? Does sigma a represent an a priori standard deviation or not? If it refers to the uncertainty of a single measurement, does that mean it is the expected error value?

Thank you