I’m currently undergoing studies and for one of my subjects I’ve performed an Elisa and got results for salivary cortisol levels using the salimetrics cortisol enzyme immunoassay kit. It says in the protocol to use a 4-parameter non-linear regression curve fit however the software I’m using SPSS Premium doesn’t seem to have this option. Is there any way anyone knows to overcome this and how would I go about using it to interpolate the concentration of my unknown samples? Any help would be greatly appreciated because I’m stressing out!
I calculated the average optical density, then corrected the error by subtracting the non-specific binding average value. I accounted for background noise in the ELISA by dividing this corrected data by the corrected optical density given by the blank sample (where concentration = 0) I have looked into all of the options in the "analyse" tab and there is no option for a 4 parameter non-linear regression, which is the method specified in the ELISA manufacturers instructions
