How can I improve regression results by adjusting the goodness of fit metric?

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SUMMARY

This discussion focuses on improving regression results by adjusting the goodness of fit metric in line fitting of experimental data using constrained Gaussians. The user employs the Levenburg-Marquadt nonlinear least squares algorithm, specifically the mpfit tool, but faces challenges due to background signals affecting the fit quality. The user seeks a metric that prioritizes fitting a subset of pixels well rather than achieving an overall mediocre fit across all pixels. The concept of least trimmed squares is identified as a potential solution for this fitting issue.

PREREQUISITES
  • Understanding of nonlinear least squares fitting techniques
  • Familiarity with the Levenburg-Marquadt algorithm
  • Knowledge of constrained Gaussian models
  • Basic principles of goodness of fit metrics
NEXT STEPS
  • Research the implementation of least trimmed squares for regression analysis
  • Explore alternative goodness of fit metrics beyond chi-squared error
  • Investigate the effects of background signals on regression results
  • Learn about advanced fitting techniques using mpfit and similar tools
USEFUL FOR

Data scientists, statisticians, and researchers involved in experimental data analysis and regression modeling, particularly those looking to optimize fitting techniques in the presence of noise or background signals.

Khashishi
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I'm doing some line fitting on experimental data. Basically I have some array of pixels, and a value measured at each pixel, and I am fitting it with several constrained Gaussians. I'm using a Levenburg-Marquadt nonlinear least squares algorithm called mpfit to fit the parameters, but the results aren't so good due to the existence of background signals in the data.

I'm thinking I could do a better fit using a different "metric" for computing goodness of fit than sum(chi squared error). I want the difference between the model function and the data to be small over many pixels, but not necessarily all of the pixels. That is, I prefer a fit that matches 10 out of 30 pixels very well (but 20 pixels very poorly) over a fit that fits all 30 pixels in a mediocre way. Has anything like this been done before? I don't want to reinvent the wheel.
 
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