Bioequivalence and Bioavailability Forum

The mysterious ρ -between or within studies [General Sta­tis­tics]

posted by d_labes  – Berlin, Germany, 2018-02-11 20:21 (2263 d 13:20 ago) – Posting: # 18399
Views: 15,460

Dear Helmut,

❝ Yep, then I expect a high correlation (based on my limited knowledge of PK). For my data sets I get with

❝ pearson <- cor.test(log(study$AUC), log(study$Cmax))


❝ rho[set, "estimate"] <- pearson$estimate


❝ rho[set, "lower"]    <- as.numeric(pearson$conf.int)[[1]]


❝ rho[set, "upper"]    <- as.numeric(pearson$conf.int)[[2]]


❝ summary(rho, digits=5)


❝


❝     estimate           lower               upper     


❝  Min.   :0.20123   Min.   :-0.094923   Min.   :0.40858
❝  1st Qu.:0.70335   1st Qu.: 0.516584   1st Qu.:0.82721

❝  Median :0.81713   Median : 0.677607   Median :0.89959

❝  Mean   :0.77413   Mean   : 0.633948   Mean   :0.86544

❝  3rd Qu.:0.90122   3rd Qu.: 0.827646   3rd Qu.:0.94461
❝  Max.   :0.98928   Max.   : 0.977336   Max.   :0.99494
Thanks for that numbers.

❝ Another question: What is a “similar experiment”?

Good question. Another question. Duno. Pilot study?
For me the hole rho story is a mystery. And rather academic.
Nobody is acting according to that theory. Not at least because the understanding of what value rho shoud have or how it could be estimated.

Taking the greater sample size from the two estimations worked in the past. So what?
Theoretically this would be the case if rho ~ 1 since then the combined power of the two TOST is the minimum of the individual powers. That would be my favoured candidate .
Be warned: rho=1 throws an error in sampleN.2TOST().

Complete thread:

• Power and type I adjustment for 222BE when several PK prams considered Louis52 2018-02-07 21:04 [General Sta­tis­tics] 
  • Power and type I adjustment for 222BE when several PK prams considered ElMaestro 2018-02-07 22:37
  • Power of two combined TOST d_labes 2018-02-08 14:12
    • The mysterious ρ Helmut 2018-02-08 21:40
      • ρ ρ ρ your boat ElMaestro 2018-02-09 09:58
        • ρ ρ ρ your boat Helmut 2018-02-09 19:20
      • ...and a bonus question ElMaestro 2018-02-09 11:32
        • ...and a bonus question Helmut 2018-02-09 19:43
          • If u see a BEar don't forget to R oaρ Astea 2018-02-09 20:47
            • package install failed d_labes 2018-02-11 13:23
      • The mysterious ρ -between or within studies d_labes 2018-02-11 15:57
        • The mysterious ρ -between or within studies Helmut 2018-02-11 17:31
          • The mysterious ρ -between or within studiesd_labes 2018-02-11 19:21
            • The mysterious ρ within studies Helmut 2018-02-11 22:44
              • The mysterious ρ within studies nobody 2018-02-12 09:08
        • The mysterious ρ -between or within studies Astea 2018-02-11 17:34
          • The mysterious ρ -between or within studies d_labes 2018-02-11 19:36
          • The mysterious ρ within studies Helmut 2018-02-11 22:48
  • Power and type I adjustment for 222BE when several PK prams considered ElMaestro 2018-02-11 18:43
    • Power and type I adjustment for 222BE when several PK prams considered nobody 2018-02-12 09:10
      • reminds me of something ElMaestro 2018-02-12 09:18
        • reminds me of something nobody 2018-02-12 09:38
          • Hammer to fall Astea 2018-02-12 18:37
            • Put the sickle to the corn Helmut 2018-02-13 01:37
              • Put the sickle to the corn Astea 2018-02-13 08:27
                • Put the sickle to the corn Helmut 2018-02-13 12:45
              • Put the sickle to the corn Relaxation 2018-02-13 10:37
                • multiple units, lag-times Helmut 2018-02-13 13:31