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Direc­tory info/maad

                                                       505 W GRAND BLVD 206
                                                       CORONA CA 91720 2121
                                                           19 DECEMBER 1992

Dear reader:

One problem which recurs again and again in the engineering environment is
centered around the so-called least-squares curve fit.  The coefficient of
linear correlation, r, is between -1 and 1.  When r is close to +1 or -1, 
good correlation is indicated; a value of r close to 0 means little or no
correlation.  Some software outputs a more quantitative measure of goodness
of fit.  Two factors are used: (1) the number of points, N, and (2) the
value of the correlation coefficient, r.  The attached documentation and
computer programs explain this quantative measure of fit and provide work-
ing models.

The graphical output of many commercial statistical packages does not in-
clude the construction of error bars.  This shortfall is closely tied to
the problem of goodness of fit.  If the line of best fit misses a large
proportion of the error bars or if it misses one or more significantly,
then there is little or no correlation.  This is true despite a value of r
different from zero---if the number of data points, N, is small.  The doc-
ument provides a vehicle for the correct graphical display of statistical

It is hoped that the user of this document and the computer programs will 
be spared from the need to constantly "re-invent the wheel."

Harry A. Watson, Jr.
(909) 737-3958

maad – Math­e­mat­i­cal Ap­prox­i­ma­tions and Doc­u­men­ta­tion

A doc­u­ment de­scrib­ing the pa­ram­e­ter­i­sa­tion of least-squares curve fit­ting, and show­ing how (us­ing PiCTeX) to dis­play er­ror bars.

Ver­sion 1994-09-02
Li­cense Public Do­main Soft­ware
Main­tainerHarry A. Wat­son, Jr
Topics ‘stand-alone’ doc­u­men­ta­tion
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