Fw: other uses for Minitab

[Joe Ward]

Hi, Tim --   It's good to hear that some folks think it is useful to fit a least-squares line through the origin.  Of course it is even better to be able to "force" a least-squares model to have a wide range of properties (restrictions). Without any connection to statistics, students should be given the opportunity to use their algebra "savvy" to impose restrictions on math models.   For example, Given a model of the form:   Y = a0 + a1*X + a2*X^2 + E   it might be of interest to "restrict" the model to:   -- Pass through the origin or -- Pass through X=1 and Y = 2 or -- Slope = 0 at X=5  (For the calculus crowd) or Many others! ----------- Using Algebra, Geometry and Trig. the "least-squares story" can be presented to students WITHOUT CALCULUS.   Minimizing "distance" from a point to a line, or plane, or hyper-plane seems to be more appealing than taking partial derivatives.  Connecting "perpendicularity" to "orthogonality" seems to work well.   -- Joe ************************************************************************ * Joe Ward                                  Health Careers High School * * 167 East Arrowhead Dr                     4646 Hamilton Wolfe        * * San Antonio, TX 78228-2402                San Antonio, TX 78229      * * Phone: 210-433-6575                       Phone: 210-617-5400        * * Fax: 210-433-2828                         Fax: 210-617-5423          * * [EMAIL PROTECTED]                                                    * * http://www.ijoa.org/joeward/wardindex.html                          * ************************************************************************  ----- Original Message ----- From: Tim Erickson <[EMAIL PROTECTED]> To: Joe Ward <[EMAIL PROTECTED]> Sent: Sunday, March 05, 2000 3:28 PM Subject: Re: other uses for Minitab | on 00.03.03 10:51 PM, Joe Ward at [EMAIL PROTECTED] wrote: | | > Ahhhh Bob, you remembered. | > | > I've been "bugging" the calculator makers for many years about including | > the least-squares model of the form: | > | > LinReg(bx), Letting the function pass through the origin. | | | just a note -- Fathom has a "lock Intercept at Zero" command for its least | squares regression, hich amounts to the same thing. | | I think it's also an interesting exercise for a (calculus?) student to | derive a formula for "b" given an arbitrary set of data and the constraint | that b must minimize the sum of squares of the residuals.  At least it was | interesting to me! | | Tim | | | ================================================================ Earl Jennings               Phone: (512) 345-0628              | 6917 Thorncliffe Dr.          e-mail address:                  | Austin, TX 78731-2955       [EMAIL PROTECTED]      | ================================================================