pkpdpkpd ● 20070403 19:45 (6433 d 21:40 ago) Posting: # 616 Views: 20,183 

While assessing BE in twogroup parallel design study, should one use nominal data or log transformed data. If log transformed, should it be log or ln? PKPDPKPD 
Jaime_R ★★ Barcelona, 20070403 20:58 (6433 d 20:27 ago) @ pkpdpkpd Posting: # 617 Views: 18,531 

Hi PKPDPKPD  what a nick! ❝ While assessing BE in twogroup parallel design study, should one use nominal data or log transformed data. Logtransformed if you are applying a multiplicative model (for all clearance based parameters, e.g., for AUC, Cmax,...) Untransformed for Tmax  if applicable to your formulation. ❝ If log transformed, should it be log or ln? Whatever you like (ld  logarithmus dualis  would also do the job), but most people prefer ln. — Regards, Jaime 
pkpdpkpd ● 20070403 21:07 (6433 d 20:18 ago) @ Jaime_R Posting: # 618 Views: 18,187 

Thank you. While using raw data and log data, I have significantly different results. In case of the parallel design, I calculate the ratio taking the mean from one group and the mean of the other group for the raw data and log of the mean from one group and log of the mean from another gruop. Am I true?  Edit: Full quote removed. [HS] 
Jaime_R ★★ Barcelona, 20070403 21:41 (6433 d 19:45 ago) @ pkpdpkpd Posting: # 619 Views: 18,086 

Hi PKPDPKPD! ❝ Thank you. While using raw data and log data, I have significantly different results. That's quite common using transformations on data. I hope you have a statistical protocol in place, and are not playing around to see which results are meeting your expectations. ❝ In case of the parallel design, I calculate the ratio taking the mean from one group and the mean of the other group for the raw data and log of the mean from one group and log of the mean from another gruop. Am I true? I guess, you are talking of untransformed analysis first and transfomed analysis second? Let's concentrate only on the transfomed analysis (because this is the one you will need).
— Regards, Jaime 
pkpdpkpd ● 20070403 22:14 (6433 d 19:11 ago) @ Jaime_R Posting: # 620 Views: 18,185 

Jaime, Thank you for your lesson. I am a beginner PKPDPKPD and am trying to understand the procedure which is normally done by the software. Just few questions to your instructions: 1. delta: should it be a difference of the raw data and log transformed data 2. why shoudl i calculate the difference not ratio PKPDPKPD  Edit: Full quote removed. [HS] 
Jaime_R ★★ Barcelona, 20070403 22:29 (6433 d 18:56 ago) @ pkpdpkpd Posting: # 621 Views: 20,017 

Dear PKPDPKPD! ❝ I am a beginner PKPDPKPD and am trying to understand the procedure which is normally done by the software. That's the best start of possible ones! Never trust in any piece of software you haven't written yourself (and even then you should be cautious…) ❝ Just few questions to your instructions: ❝ 1. delta: should it be a difference of the raw data and log transformed data After you have logtransformed the data, you are only working with these (in my example the Ys and not the Xs) ❝ 2. why shoudl i calculate the difference not ratio Since we are now in the logdomain, we have transformed the multiplicative model (which would call for ratios!) into an additive model (therefore we are interested in differences of logs). May be sound confusing, but once you have applied the transformation, all the nice examples given in statistical textbooks (99% are based on differences!) are working now… Actually you can boil it down into three steps:
— Regards, Jaime 
pkpdpkpd ● 20070403 23:48 (6433 d 17:37 ago) @ Jaime_R Posting: # 622 Views: 18,152 

Should AUC and Cmax be also calculated from the log transformed data?  Edit: Full quote removed. Please see this post! [HS] 
Jaime_R ★★ Barcelona, 20070404 17:14 (6433 d 00:11 ago) @ pkpdpkpd Posting: # 623 Views: 18,535 

Dear PKPDPKPD! ❝ Should AUC and Cmax be also calculated from the log transformed data? See my first post. You should only transform the calculated PK parameters (not the concentrations).
Let's misuse Helmut's data (download here) Although his data are from a crossover study, we will use only period 1.
83.657% (63.514%  110.189%) I checked the 'manual' calculation in WinNonlin and EquivTest: WinNonlin: 83.6572% (63.5100%  110.1958%) EquivTest: 83.66% (63.51%  110.18%) Slight differences seen in results are not uncommon... — Regards, Jaime 
Helmut ★★★ Vienna, Austria, 20070404 17:31 (6432 d 23:54 ago) @ Jaime_R Posting: # 624 Views: 18,636 

Hi Jaime! You recycled my data! ❝ So the final results are (point estimate and 90% confidence interval): ❝ 83.657% (63.514%  110.189%) ❝ WinNonlin: 83.6572% (63.5100%  110.1958%) ❝ EquivTest: 83.66% (63.51%  110.18%) ❝ ❝ Slight differences seen in results are not uncommon... Full ACK! I don’t know which versions you were using; I'm getting exactly the same results in WinNonlin (v5.2) and EquivTest/PK. Kinetica (v4.4.1) comes up with: 83.6572% (63.514% – 110.19%) You never know when rounding will hit you – and don’t dare asking the software vendor for the algorithm… — Diftor heh smusma 🖖🏼 Довге життя Україна! _{} Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. 🚮 Science Quotes 
pkpdpkpd ● 20070404 19:32 (6432 d 21:53 ago) @ Helmut Posting: # 625 Views: 18,091 

Thank you to all. It was a great help. PKPDPKPD 
Jaime_R ★★ Barcelona, 20070404 22:33 (6432 d 18:52 ago) @ Helmut Posting: # 626 Views: 18,054 

Hi Helmut! ❝ You recycled my data! Sure! You wrote: You may use the data to 'play around' in your own piece of software. ❝ I don’t know which versions you were using… WinNonlin (v5.1.1), EquivTest (v2.00) — Regards, Jaime 
Sathya ☆ India, 20080901 09:21 (5917 d 08:04 ago) @ Jaime_R Posting: # 2291 Views: 17,372 

HAI Jaime_R, Your BE parallel design calculation is very useful to me. This is the first time i am doing Parallel Design. Thank You. I already did one BE cross over design. there i Come across the Statistical calculation like testmean refmean Standard Error Mean Standard Error diff ratio intra_cv upper lower Power P1 and P2 But in Paralled Design the Statistical calculation testmean refmean SD Variance Delta diff Q R Point Estimate Lower & Higher I have a doubt that, is there no power calculation in Parallel design? I don't know whether both parallel & crossover have same calculation or different Please Clarify. and also help me how to do power calculation in cross over? — Sathya 
Sathya ☆ India, 20080904 14:37 (5914 d 02:48 ago) @ Jaime_R Posting: # 2314 Views: 17,240 

Dear Jaime, I tried your sample Data I got some clarity in Parallel study. How can i Proceed it is in SAS? Please Help me. Please give me a sample for cross over study like parallel study especially for power calculation. Then it will be very helpful to me. can you please — Sathya 