Bioequivalence and Bioavailability Forum

Theta?! [Software]

posted by Helmut  – Vienna, Austria, 2009-10-01 19:30 (6103 d 03:59 ago) – Posting: # 4287
Views: 32,554

Dear Yuvraj!

❝ I have read the sample size calculation formula for parallel design.

Which one? Can you come up with a reference?

❝ I have one query regarding parameter Theta

Theta (θ) commonly refers to the regulatory ‘goalposts’ or acceptance limits. For an acceptable difference (Δ) of 0.2 (or 20%) in the multiplicative model we get:

θ₁ = 1–Δ (80%), and
θ₂ = 1/(1+Δ) = 1/θ₁ (125%).
In the logarithmic domain the acceptance range is symmetric around zero, since
ln(θ₁) = –0.2231 and
ln(θ₂) = +0.2231.

In the linear model (untransformed data):

θ₁ = 1 – Δ (80%), and
θ₂ = 1 + Δ (120%).

❝ Theta=(muT-muR)/muR

❝ is it a T/R ratio ?

No, this is the difference normalized to the reference.
T =  95, R = 100 ⇒ –0.05 (ratio 0.95)
T = 190, R = 200 ⇒ –0.05 (ratio 0.95)

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


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Complete thread:

• Sample Size Calculation sasikumar 2008-04-03 09:19 
  • Sample Size Calculation (SAS) Jaime_R 2008-04-03 13:13
  • Sample Size Calculation d_labes 2008-04-23 11:54
    • Sample Size Calculation balakotu 2009-09-07 07:51
    • Sample Size Calculation yuvrajkatkar 2009-09-19 09:24
      • Paper, pencil, brain ;-) Helmut 2009-09-19 11:48
        • Paper, pencil, brain ;-) yuvrajkatkar 2009-09-21 15:10
          • Paper, pencil, brain ;-) Helmut 2009-09-21 15:23
          • Paper, pencil, brain ;-) Helmut 2009-09-21 18:33
            • Paper, pencil, brain ;-) yuvrajkatkar 2009-09-22 16:09
              • No paper, pencil, brain :-( Helmut 2009-09-22 18:22
                • about your lectures yuvrajkatkar 2009-09-23 07:27
                  • About Trust Helmut 2009-09-23 13:50
                    • sample size calculation yuvrajkatkar 2009-10-01 13:33
                      • inter- / intra- / total variance Helmut 2009-10-01 13:52
                        • inter- / intra- / total variance yuvrajkatkar 2009-10-01 17:13
                          • Theta?!Helmut 2009-10-01 17:30
                            • sample size for parallel design yuvrajkatkar 2009-10-03 07:44
                              • Reference? Helmut 2009-10-03 13:46
                                • MSE obtain from Parallel study in WinNonlin yuvrajkatkar 2009-10-09 16:46
                                  • Parallel study in WinNonlin Helmut 2009-10-10 10:51