< Back to calibration programs In a slope ratio assay the responses of dilutions of a standard are compared with the responses of dilutions of a test sample. The two lines have an intersection point at
dosis = 0 — the intercept is identical in both equations. 

The SRA presented here is written in Microsoft Excel and is an copy of the method described by D.J. Finney Two versions are available. 

The use of the program is straight forward. Enter the doses and responses of the sample and the standard in multiplo and the blanks of the test The calculated slope is multiplied by predilution and by the calculated potency of the standard. The three Ftests are used to validate the test Blank is to test if the calculated slope intersects with the mean of the blanks Intercept tests if the standard and the sample lines intersect at dosis is zero. curvature test if the line are straight and not curved. If one of these Ftests is greater than the Fcritical the calculated potency must be rejected. 
Reference: "Statistical Methods in Biological Assays" D.J.Finney
It is good to hear if you like this free program.
< Back to calibration programs
Ed Nieuwenhuys, 9 july 2009