Limits to EObs

Phoenix Certara Forums Modelling and Simulation
1

I have some activity data from mice in time bins. The observed data is in percent of time they are mooving. If the mice are stimulated many will move around 100% of the time. However, some of the mice that moove 100% of the time are more stimulated than others so we observe a ceiling effect. So the real Emax is higher than the observed Emax which is limited by a ceiling of the measurements. I would like to convert my PD model with a ceiling effect so that. eg (0,0.3,0.9,1.2,1.5) preddicted from the model is converted to (0.30,90,100,100). I tried

logit(Emax*E/EC50+E)

or

E= ln (EB / (1 - EB))

EB= Emax*E/EC50+E

However both ln and logit does not work in the model structure. Is there another way to do this effect prediction with a ceiling?

BR Frederik

2

HI Frederik,

you might need a trauncated model where you have an upper limit of quantification here Emax

you will need to write your LL statment as we do not have this built in.

Bests,

Samer

3

ok. I will look into how to write my own LL statement.

Thx Frederik

4

also look at : https://support.certara.com/forums/topic/1189-how-to-deal-with-values-above-the-upper-limit-of-quantification/?hl=%2Bupper+%2Blimit