(35S) Linearized S-Curve (Logistic Curve) Regression

[Dieter]

(03-12-2018 11:36 AM)PedroLeiva Wrote:  After Dieter´s corrections I would like to test with a numerical example; could you please post some example to illustrate.

For F=100 assume the following data:

Code:

T   1   2   3   4   5
S  20  40  70  80  95

Start program:

Code:

[XEQ] S [ENTER]
F?  100 [R/S]

Enter data pairs:

Code:

S?  20 [R/S]
T?   1 [R/S]

S?  40 [R/S]
T?   2 [R/S]

S?  70 [R/S]
T?   3 [R/S]

S?  80 [R/S]
T?   4 [R/S]

S?  95 [R/S]
T?   5 [R/S]

Calculate regression:

Code:

XEQ F [ENTER]
              R=-0,9921
   [R/S]      R= 0,9842   // this is r²
   [R/S]      B= 2,4587   // this is ln b (!)
   [R/S]      B= 11,6898
   [R/S]      C= 1,0453

Forecast T => S:

Code:

   [R/S]      T? 
 2 [R/S]      S= 40,9008
   [R/S]      T?
 6 [R/S]      S= 97,8400

BTW, I would remove the output of ln b (line F014 and F015) since this can be misleading. The value is ln b but the display says it's b. The same is true for the regression coefficient. I'd simply display r here ("R=") and have r² in X so that it may be displayed by pressing the [<=] key, if required.

Dieter