TI36X Pro: Stat: x’ and y’ estimates for Exp, Log, Power curves.

12042022, 11:45 PM
(This post was last modified: 12042022 11:49 PM by Matt Agajanian.)
Post: #1




TI36X Pro: Stat: x’ and y’ estimates for Exp, Log, Power curves.
Hi all.
I see that I can calculate xestimate and yestimate for linear/ax+b data right from the STAT mode. I don’t see that function when I use other curve models. Or are there x' and y' functions in stat mode for the other regression models? Although the formula can be stored in f(x) and use numsolve to calculate x’ and y’. Do a and b carry over into register a & b so I can use them in numsolv for solving the equation placed in f(x) for x’ and y’? 

12062022, 12:08 AM
(This post was last modified: 12062022 12:31 AM by ijabbott.)
Post: #2




RE: TI36X Pro: Stat: x’ and y’ estimates for Exp, Log, Power curves.
(12042022 11:45 PM)Matt Agajanian Wrote: Hi all. a and b do carry over into variables and the regression formula can be saved to f(x) (or alternatively to g(x) on the TI30X Pro MathPrint). Yes, you can use numsolv on the f(x) (or g(x)) function saved by the regression calculation to solve x' for f(x')=y' or (g(x')=y'). Alternatively, a and b variables can be used to calculate x' from the inverse function. For example, for ExpReg ab^x, calculate x' = ln(y'/a)/ln(b) directly on the Home screen. For y', just evaluate the function f(x') (or g(x')). As you guessed, the x'() and y'() functions on the 2Var Stats menu assume linear regression. — Ian Abbott 

12062022, 02:22 AM
(This post was last modified: 12062022 03:06 AM by Matt Agajanian.)
Post: #3




RE: TI36X Pro: Stat: x’ and y’ estimates for Exp, Log, Power curves.
(12062022 12:08 AM)ijabbott Wrote:(12042022 11:45 PM)Matt Agajanian Wrote: Hi all. Yeah. I noticed that the LinReg model is what the 36X Pro uses. Can’t wait for my 30X Pro MathPrint so that the big three (Log, Pwr, Euler Exponential) are available to be calculated. Then, as you said that the Linear regression model is used for x’ and y’ calculations on the 36X Pro. With this in mind, since Euler’s Exponential model is lacking on the 36X Pro, I just went back to the HP34C’s Curve Fitting principles to enter data and calculate a, b, r, r^2, y’, and x’. 

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