lin-up/log-down is bear’s default [🇷 for BE/BA]

posted by Helmut Homepage – Vienna, Austria, 2017-05-21 19:32 (2503 d 18:48 ago) – Posting: # 17380
Views: 7,768

Dear Pjs,

❝ […] this wonderful freeware


bear = free software (open source) ≠ freeware. :-D

❝ […] if i do manual calculation of AUC by trapezoid rule by formula, AUC is coming to 1478.681 instead of 1435.682 by bear.


Note that the lin-up/log-down trapezoidal method is the default in bear – and for good reasons (IMHO, the linear rule should abandoned since it overestimates the AUC in the distribution/elimination phase). I got:

 time    conc     bear   incr/equal  linear   lin/log
 0.00    0.000     0.000    yes      0.000      0.000
 1.00    0.000     0.000    yes      0.000      0.000
 1.50    0.000     0.000    yes      0.000      0.000
 2.00    0.000     0.000    yes      0.000      0.000
 2.50    0.000     0.000    yes      0.000      0.000
 3.00    0.000     0.000    yes      0.000      0.000
 3.50    0.000     0.000    yes      0.000      0.000
 4.00    1.518     0.380    yes      0.380      0.380
 4.33    5.027     1.459    yes      1.459      1.459
 4.67   12.700     4.473    yes      4.473      4.473
 5.00   22.210    10.233    no      10.233     10.088
 5.33   18.013    16.846    yes     16.870     16.725
 5.67   22.332    23.704    yes     23.729     23.583
 6.00   30.500    32.422    no      32.446     32.231
 6.33   24.290    41.423    yes     41.486     41.271
 6.67   31.676    50.937    yes     51.000     50.785
 7.00   32.647    61.551    yes     61.614     61.398
 7.50   45.512    81.091    yes     81.154     80.938
 8.00   95.827   116.425    yes    116.488    116.273
10.00  120.261   332.513    no     332.576    331.437
12.00   89.598   540.870    no     542.435    539.794
16.00   41.572   791.036    no     804.775    789.960
24.00   24.576  1049.699    no    1069.367   1048.623
36.00    9.237  1237.802    no    1272.245   1236.725
48.00    4.897  1319.870    no    1357.049   1318.793
72.00    1.976  1397.115    no    1439.525   1396.039
96.00    1.287  1435.682    no    1478.681   1434.606


Lin-up/log-down trapezoidal method:
If concentrations are increasing or equal in the interval [1, 2] use the linear trapezoidal, i.e.,

AUC1–2 = 0.5(t2–t1)(C2+C1)

If concentrations are decreasing in the interval [1, 2] use the log trapezoidal, i.e.,

AUC1–2 = (t2–t1)(C2–C1)∕log(C2∕C1)


1435.682 ≠ 1434.606. Close, but… Is it possible that in your original data set times and/or concentrations are given with more significant digits than you posted here? Please check.

If you have to use the linear trapezoidal method (stupid SAP, SOP, boss), see this post and change the Setting for trapezoidal AUC from 0 to 1.

Dif-tor heh smusma 🖖🏼 Довге життя Україна! [image]
Helmut Schütz
[image]

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

Complete thread:

UA Flag
Activity
 Admin contact
22,957 posts in 4,819 threads, 1,636 registered users;
106 visitors (0 registered, 106 guests [including 9 identified bots]).
Forum time: 13:21 CET (Europe/Vienna)

With four parameters I can fit an elephant,
and with five I can make him wiggle his trunk.    John von Neumann

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5