Weighting of non-linear fit
1 view (last 30 days)
Show older comments
I have made a rational fit function of some data using the cftool GUI. It works quite well.
I have some data points (X,Y) with standard error Ye (Y +/- Ye).
At first I made the rational fit model simply using the X,Y data points. But then I decided that I wanted to include the Y uncertainty of the data points in to model somehow. So I used weighting (w) to represent this, whereby:
w(i) = 1 / (Ye(i)^2))
w is a 1 by length(y) matrix
However, I am a bit puzzeled. When I plot the model with observation bounds, I get larger observation bounds when I plot the unweighted model than when I plot the weighted model.
I thought that since the weighted model included data point uncertainty, that the observation bounds should be larger?
Have I done something wrong or am I just not yet understanding something that perhaps at first seems unintuitive?
Find more on Get Started with Curve Fitting Toolbox in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!Start Hunting!