How is the Probit LC50 estimation table calculated in SPSS?

[Ricardo H]

Hello, I am doing a data run in SPSS to determine Lethal Dose 50 using the Probit Model.

After running Probit, it gives me a model (equation) and a table of probit values vs estimated doses.

https://drive.google.com/file/d/1O-vGSxmzH-3_nwzbHqezfV_6qckV97e_/view?usp=share_link

https://drive.google.com/file/d/12fxURZqDntRdW254HE2yRXsyHKH_BmHo/view?usp=share_link

However, when I plug values into the equation to check what I see in the table, I don't get the values it shows me.

https://drive.google.com/file/d/1fRAYC0cCgvReWdKPYTnDPtkzqZ-uNPQ_/view?usp=share_link

My question is: How, with what calculation, are the values of the Probit vs. Dose estimation table obtained in SPSS?

[Rich Ulrich]

On Thu, 17 Nov 2022 13:49:04 -0800 (PST), Ricardo H

Post by Ricardo H
Hello, I am doing a data run in SPSS to determine Lethal Dose 50 using the Probit Model.
After running Probit, it gives me a model (equation) and a table of probit values vs estimated doses.
https://drive.google.com/file/d/1O-vGSxmzH-3_nwzbHqezfV_6qckV97e_/view?usp=share_link
https://drive.google.com/file/d/12fxURZqDntRdW254HE2yRXsyHKH_BmHo/view?usp=share_link
However, when I plug values into the equation to check what I see in the table, I don't get the values it shows me.
https://drive.google.com/file/d/1fRAYC0cCgvReWdKPYTnDPtkzqZ-uNPQ_/view?usp=share_link
My question is: How, with what calculation, are the values of the Probit vs. Dose estimation table obtained in SPSS?

That's probably documented with other algorithms.

Borrowing from a recent post by Bruce,
Try posting to the SPSSX-L mailing list that is maintained by the
University of Georgia. It is far more active than this newsgroup.
You can join and post via this website:

https://listserv.uga.edu/scripts/wa-UGA.exe?INDEX

I hope this helps.