Bioequivalence and Bioavailability Forum

Spaghetti & other pasta [NCA / SHAM]

posted by Helmut  – Vienna, Austria, 2013-05-23 17:15 (3989 d 21:19 ago) – Posting: # 10630
Views: 17,478

Dear Yung-jin,

❝ ❝ ❝ Otherwise, the line should not be connected in that way. It should be connected as the line that the arrow points.

❝ ❝ Why?

❝ Sorry, I thought it was using lin-up/log-down algo and plots in slide#17.

We are all guilty in not representing in spaghettis plots the method we use for calcu­lat­ing the AUC. For simplicity we connect point with straight lines, regardless whether we use a linear or semilogarithmic scale (all left panels below).
If we use the linear trapezoidal, the semilog plot is wrong. What we are actually cal­cu­lating would be reflected in the lower right.



Weird, isn’t it? But then hopefully everybody would realize that the algo overestimates AUCs in the distribution / elimination phase.

On the other hand if we use the lin-up/log-down trapezoidal the linear plot is wrong; should use the upper right one instead.



Have you ever seen something like this before? I didn’t. Would be a tough job to come up with such a setup in commercial software.

PS: Very rarely you find publications where in mean plots the points are not connected by lines at all.
PPS: What do you think about adding rug(t, side=3) to plots in bear?

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна! 
Helmut Schütz


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Science Quotes

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 pastaHelmut 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 pasta yjlee168 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