I have a data set with data that is y vs time ( and nonlinear). It has been sampled at uneven times and has missing dataetc. So to compare the data I have interpolated (by linear interpolation) to new time points for all the data using software (matlab). The data set is massive so I have automated this process so checking the fit visually is difficult. Does anyone know of a way to calculate the "fit" of the interpolated data? As they are original data and resembled data are at new time points, I cannot think of a way to do this. Or is there a better way resampling the data and calculating the fit?