HP 48G Linear Regression Best Fit Line

[Rodger Rosenbaum]

(12-22-2021 02:09 AM)MNH Wrote:  After you do the "Fit data" in the statistics menu, there are 3 items on the stack--just drop them.

Done

Execute LR; what do you see on the stack? It should be error free--drop anything on the stack.

Intercept: 672.349
Slope: 0.008

Execute ORTH (press the softkey for ORTH); what do you see on the stack? it should be error free--clear the stack.

0.008
672.345

Edit: See the post right after this one.

I see a possible problem here. The result from running ORTH should not be two separate values on the stack as you apparently show like this:

Level 2: 0.008
Level 1: 672.345

The result should be a 2 row, 1 column matrix like this:

[[ 0.008 ]
[ 672.345 ]]

So, which is the ORTH result, two values or a matrix?

(12-22-2021 02:09 AM)MNH Wrote:  You can run OFIT manually a step at a time. Recall X to the stack by pressing the softkey for the X variable; what do you see?

x matrix

Press the softkey for ORTH; what do you see?

x matrix
0.008
672.345

Type "DUP" and press enter; what do you see?

x matrix
0.008
672.345
672.345

Type "1." and press enter; what do you see?

x matrix
0.008
672.345
672.345
1.000

Type "GET" and press enter; what do you see?

GET Error:
Bad Argument Type
0.008
672.345
672.345
1.000

Apparently the error will occur when we try to execute "GET", so the contents of the stack here, and just before the "GET", should tell us what the problem is.