Aiming at the experimental data in the process of calibration and comparison of measurement system
based on the least square method and Lagrange method
data fitting methods between two variables and their uncertainty expressions are studied.Two cases are considered.One takes into consideration uncertainty of independent variable
and the another neglects uncertainty of independent variable in fitting process.Two kinds of fitting results were given and compared by using a set of real experimental data.It is concluded that the fitting uncertainty in the first case is less than that in the second case.