Bioequivalence and Bioavailability Forum • Spaghetti & other pasta

Spaghetti & other pasta [NCA / SHAM]

posted by yjlee168 – Kaohsiung, Taiwan, 2013-05-24 00:46 (4363 d 11:35 ago) – Posting: # 10634
Views: 19,353

Dear Helmut,

Thanks again. Now I think that I have fully understood the differences between the linear and the lin-up/log-down method for AUC calculations. Actually, lin-up/log-down method is still a kind of data smoothing approach. It is applied to calculate more accurate AUC than the linear one. Some people should not get crazy when using lin-up/log-down if they can see the differences here. Just because the line is too smooth to be true? That may scare people a little bit. That's why I asked if you used some kinds of data smoothing methods in previous message. The key point is that involved calculation step still uses the raw data to calculate the interpolated data. As we can see, the errors between linear and lin-up/log-down become significantly apparent, especially when sampling time between two data points is getting greater. Therefore, when there is missing data occurring, the lin-up/log-down method shows more accurate than the linear.

❝ [...]

❝ I have no experiences with SAS, but in Phoenix/WinNonlin it is tricky indeed.

should be no problem at all. They are professional after all.

❝ [...]

❝ It was just an idea to display the sampling schedule. Forget it. ;-)

I see. However, it could be misunderstood or confused by people to interpret it (the rug) as a 'log scale' with x axis.

—
All the best,
-- Yung-jin Lee
bear v2.9.2:- created by Hsin-ya Lee & Yung-jin Lee
Kaohsiung, Taiwan https://www.pkpd168.com/bear
Download link (updated) -> here

Complete thread:

handling of missing data gracehung 2013-05-20 07:35
- Lin-up/log-down trapezoidal avoids most trouble Helmut 2013-05-20 14:22
  - Lin-up/log-down trapezoidal avoids most trouble yjlee168 2013-05-22 08:25
    - Multiple peaks: fallback to linear trapezoidal Helmut 2013-05-22 20:25
      - Multiple peaks: fallback to linear trapezoidal yjlee168 2013-05-22 21:57
        
        No interpolation Helmut 2013-05-22 23:25
        
        No interpolation yjlee168 2013-05-23 11:43
        
        Spaghetti & other pasta Helmut 2013-05-23 15:15
        
        Spaghetti & other pasta yjlee168 2013-05-23 20:47
        
        Spaghetti & other pasta Helmut 2013-05-23 21:29
        
        Spaghetti & other pastayjlee168 2013-05-23 22:46
        
        Spaghetti & other pasta Helmut 2013-05-24 01:24
        
        Spaghetti & other pasta yjlee168 2013-05-24 09:17
        
        No interpolation Ken Peh 2013-05-30 19:55
        
        Different algos! Helmut 2013-05-30 22:38
        
        Different algos! Ken Peh 2013-06-03 17:52
        
        Calculate what? Helmut 2013-06-03 18:11
    - Lin-up/log-down trapezoidal example Helmut 2013-05-25 15:09
      - Lin-up/log-down trapezoidal example yjlee168 2013-05-25 19:45
- handling of missing data Ohlbe 2013-05-20 21:45
  - Sorry Helmut 2013-05-21 13:53
    - Sorry gracehung 2013-05-23 01:06
      - Uncertain time point Helmut 2013-05-23 01:35