Bioequivalence and Bioavailability Forum

EquivTest v1 / v2 / PK [Software]

posted by Helmut  – Vienna, Austria, 2008-05-27 17:41 (6190 d 02:35 ago) – Posting: # 1875
Views: 8,927
(edited on 2008-05-27 19:47)

Dear Yu!

❝ I found the difference of mean calculation method between equivtest 1.0 and 2.0.

Fascinating! I have both versions on my machine and will check it sometime...

❝ Equivtest 1.0 calculates (mean_seq1+mean_seq2)/2 instead of {(mean_seq1*n1)+(mean_seq2*n2)}/(n1+n2). The company confirmed Equivtest 2.0 is right. Which is the right one in your opinion?

In the case of an unbalanced study (n₁ # n₂) only the latter.

❝ Is the other method absolutely wrong?

If the design is balanced (n₁ = n₂), the second formula reduces to the first one. In technical terms, the second one is wrong for unbalanced studies; the bias will depend on both the overall size of the study (n₁+n₂) and the degree of unbalance (ratio of n₁/n₂).

❝ I would also like to know the theoretical basis.

There are some examples in Chow & Liu (2001).

--
Edit: Sorry, I don't have version 1 any more. Both EquivTest02.00 (2001) and EquivTest/PK (2006) use the correct formula - which is also given in the manuals (look for TOST).

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Helmut Schütz


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Complete thread:

• Mean calculation method in unbalanced cross-over study yckim 2008-05-27 15:04 
  • EquivTest v1 / v2 / PKHelmut 2008-05-27 15:41
    • EquivTest v1 / v2 / PK yckim 2008-05-28 01:39
      • Weighted mean Helmut 2008-05-28 11:55
        • Least square mean d_labes 2008-05-28 16:35
          • Least square mean yckim 2008-06-03 07:46
            • Least square mean JPL 2008-06-03 09:10
              • Least square mean vish14184 2008-06-04 06:54
                • Least square mean JPL 2008-06-04 08:44