Stat2Var bug sketch plot - Printable Version +- HP Forums ( https://www.hpmuseum.org/forum)+-- Forum: HP Calculators (and very old HP Computers) ( /forum-3.html)+--- Forum: HP Prime ( /forum-5.html)+--- Thread: Stat2Var bug sketch plot ( /thread-6120.html) |

Stat2Var bug sketch plot - akmon - 04-23-2016 10:11 PM
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? RE: Stat2Var bug sketch plot - Tim Wessman - 04-25-2016 03:00 PM
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! |