Linear Least Squares Regression©
Sidney H. Young
**Sid Young died in 2004 after a long illness. He was a beloved teacher and a leader in the development and use of Mathcad as a tool to promote student learning in physical chemistry. A memorial to Dr. Young was established by the University of South Alabama ACS Student Affiliate, http://www.southalabama.edu/acs/memorial.html

Andrzej Wierzbicki
Department of Chemistry
University of South Alabama
Mobile, AL 36688
United States
mail to: wierzb@andy.chem.usouthal.edu

Linear least squares regression is the workhorse of the Physical Chemistry Laboratory. This template demonstrates various implicit and explicit methods for determination of slope and intercept of a regressed line. It also produces the correlation coefficient, 95% confidence ranges, standard deviation of fit, standard deviation of slope and standard deviation of intercept. Residual analysis is used to demonstrate techniques of determining and removing questionable data points from the fit. This template reads in data from an external files. This permits using the template to be used as a general laboratory tool.

Occasionally data is poorly fit with a linear least squares model. In this case, a quadratic term can be added to improve the fit. A second set of data will be analyzed which includes a quadratic term for improved fitting. A statistical test determines whether the quadratic term is statistically significant. This testing method is general and can be used for all fitted parameters.

Both versions share the same pdf file. The operational differences that occur in the active documents occur because of differences in the Readprn command and that the function Stdev in version 8 is not supported in version 6.
Editor's Commentary
Audiences: Upper-Division Undergraduate
Pedagogies: Computer-Based Learning
Domains: Analytical Chemistry, Laboratory Instruction, Physical Chemistry
Topics: Chemometrics, Mathematics / Symbolic Mathematics
File NameDescriptionSoftware TypeSoftware Version
LinearLeastSquares.mcd JCE Mathcad Computational Document (Requires Mathcad 8) Mathcad 8
LinearLeastSquares.pdf Read-Only Document mathcad Mathcad
data1.prn JCE Data File
exercise22x.prn JCE Data File
exercise22y.prn JCE Data File
linear_x.prn JCE Data File
linear_y.prn JCE Data File
JCE JCE Subscribers only: name and password or institutional IP number access required.
Young, S. H.; Wierzbicki, A. J. Chem. Educ. 2000 77 669.
Comments to: Andrzej Wierzbicki at wierzb@andy.chem.usouthal.edu
©Copyright 2004 Journal of Chemical Education