Negative values in 95%CI on ETAs

From:"MANOJ KHURANA" manoj2570@yahoo.com Subject: [NMusers] Negative values in 95%CI on ETAs Date: Tue, November 16, 2004 2:03 pm Hello All, I am a novice nonmem user and out of my first crawls on this floor I am here with a querry. I am trying to model an oral absorption data aftter escalating doses using ADVAN4 TRANS1 with KA fixed due to rapid absorption (Data apppears to follow 2-comp and obviously parametrization using TRANS3 didnt work well even after fixing KA). With the current model I have good estimates of Thetas (K, K23, K32 and V2) but 95%CIs on the ETAs have negative values (I have all EXP ETAs on all THETAs) with very high %RSE. Can anybody suggest whats missing and if I am wrong somewhere. Thanks MK