Re: Logit scale? Was Re: New patch supporting nonlinear axes

[Nicolas B. (I. <br...@IN...>]

Resent because of the limitation to 150k of the gnuplot-beta mailing list!

Dear Ethan,


I looked back at the data that I used when I was looking for a plotter which could do logistic scale.
It was before the new law on abortion (2001) which made legal the 11th and and 12th week of pregnancy.
But any cumulative distribution could be of interest.
I did not install yet the patch but a possible code could be (notice that “expit" is the standard expression for inverted logistic):
logit(p) = log(p/(1-p))
expit(a) = 1. / (1. + exp(-a))
set nonlinear y via expit(y) inverse logit(y)
plot [.001:.999] "Agegestationnel.txt" u 1:3 w l,"" u 1:4 w l , "" u 1:5 w l, "" u 1:6 w l,  "" u 1:7 w l, "" u 1:8 w l,  "" u 1:9 w l, "" u 1:10 w l,  "" u 1:10 w l,  "" u 1:11 w l,  "" u 1:12 w l,  "" u 1:13 w l
I can test it.

Here is what I got from Excel in year 2000!