Bioequivalence and Bioavailability Forum 04:50 CET

Main page Policy/Terms of Use Abbreviations Latest Posts

 Log in |  Register |  Search

The mysterious ρ -between or within studies [General Sta­tis­tics]

posted by Astea - Russia, 2018-02-11 17:34  - Posting: # 18397
Views: 7,399

(edited by Astea on 2018-02-11 17:54)

Dear Detlew!

Thank you very much for the explanation! Now I've got it! (Yes, multitasks harm..)

So, for ρ=0.8 I get now
type1error.2TOST(CV=c(0.3, 0.25), n=122, theta1=c(0.8, 0.9),
                 theta2=c(1.25, 1/0.9), rho=0.8, details=TRUE)
1e+06 simulations. Time consumed (secs)
   user  system elapsed
 979.75   95.18 1115.72
  Intersection null P(Type I Error) theta0 #1 theta0 #2
1      H_A01 n H_Ca        0.048904 0.8000000  0.953047
2      H_A02 n H_Ca        0.049193 1.2500000  1.056122
3      H_Aa n H_C01        0.049620 0.9709781  0.900000
4      H_Aa n H_C02        0.050024 1.0000000  1.111111
5     H_A01 n H_C01        0.024479 0.8000000  0.900000
6     H_A01 n H_C02        0.000000 0.8000000  1.111111
7     H_A02 n H_C01        0.000000 1.2500000  0.900000
8     H_A02 n H_C02        0.024451 1.2500000  1.111111
and inflation at 0.050024

As I understand estimated from several datasets ρ is "between studies" ρ while in Power2TOST we need to use "within studies ρ". But it may be interesting while discussing multicomponent drugs. Especially question may arise for two components, when one of them is HVD while other is not and different approaches or CI limits involved (like telmisartan+amlodipine).
The intermediate question is mentioned situation about parent drug and its metabolite - logically, the correlation for the parameters of parent drug and its metabolite should be stronger than for two different drugs tested on the same population?

Dear Helmut!
Do I understand correctly that in your latest code you exployed all AUC and Cmax individual data for each study in order to estimate "within rho"?

Complete thread:

Activity
 Mix view
Bioequivalence and Bioavailability Forum |  Admin contact
19,154 posts in 4,080 threads, 1,308 registered users;
online 11 (0 registered, 11 guests [including 9 identified bots]).

One can show the following: given any rule, however “fundamental”
or “necessary” for science, there are always circumstances
when it is advisable not only to ignore the rule,
but to adopt its opposite.    Paul Feyerabend

The BIOEQUIVALENCE / BIOAVAILABILITY FORUM is hosted by
BEBAC Ing. Helmut Schütz
HTML5 RSS Feed