Stat2Var bug sketch plot

04232016, 10:11 PM
Post: #1




Stat2Var bug sketch plot
Hello. Sketch plot is a very interesting function for best fit given some points. I wanted to know how accurate is my finger calculating R^2 stats after sketching. I made a very simple example given these points:
0,0 1,1 2,2 3,3 4,4 After drawing the points I sketch with my finger a sort of line, for example: Y=0,6*X+1 When I go to stats sheet, the first colum represents the linear fit (itÂ´s done automaticaly by HP Y=X), and the second column is the equation I obtained by sketching the line with my finger. It gets unexpected values. Moreover the more I press STAT softmenu, the more the values changes: Have I discovered a bug? 

04252016, 03:00 PM
Post: #2




RE: Stat2Var bug sketch plot
I believe so. Note that you still wouldn't get a R^2 value in there because it isn't a true regression but acts as a "user function". It would behave the same way as doing one of the other regresisons, then modifying the equation. The type changes to "user" and has much more limited capability.
A lot of people seem to have the idea that R^2 is simply a collection of the error and can be done for any regression type. In actuality, it is defined exclusively for the linear based ones, and with a slight extension for polynomial. (unless I am remembering wrong from when I was implementing things...) Anyway, shouldn't be showing those funny looking results there. Thanks! TW Although I work for the HP calculator group, the views and opinions I post here are my own. 

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