Bioequivalence and Bioavailability Forum • Histogram charlatanry

Histogram charlatanry [Two-Stage / GS Designs]

posted by Helmut – Vienna, Austria, 2015-06-09 15:43 (3237 d 20:47 ago) – Posting: # 14932
Views: 17,771

Dear Detlew!

❝ Wow! That made me dumbfounded! Clever, clever.

❝ :clap:

THX for the premature praise. Unfortunately my code is just approximate (euphemism for quick & dirty):

mean(N)

[1] 42.25025

Whereas correct is

power.2stage(CV=0.3, alpha=c(0.001, 0.0413), n1=24, print=F, details=F)$nmean

[1] 42.26836

If one wants to get the histograms right, download the source from CRAN and after the line
} # end stage 2 calculations
add
hist <- hist(ntot, plot=FALSE)
At the res-list change the last line to

  nmean=mean(ntot), nrange=range(ntot), nperc=quantile(ntot, p=npct),

  hist=hist)

Now the data needed to plot a histogram of the total sample size are accessible for further use:

CV  <- 0.3

n1  <- 24

col <- "#AAF7FF"

alpha <- matrix(nrow=4, ncol=2, byrow=T, dimnames=list(

  c("Haybittle/Peto 0.0010/0.0413",

    "O\u2019Brien/Fleming 0.0050/0.0416",

    "Zheng 0.0100/0.0412",

    "Potvin 0.0302/0.0302"),

  c("alpha1", "alpha2")))

alpha[1, ] <- c(0.001, 0.0413)

alpha[2, ] <- c(0.005, 0.0416)

alpha[3, ] <- c(0.010, 0.0412)

alpha[4, ] <- rep(0.0302, 2)

invisible(split.screen(c(2, 2)))

for(j in 1:nrow(alpha)) {

  screen(j)

  res <- power.2stage(CV=CV, alpha=alpha[j, ], n1=n1, print=F, details=F)

  plot(res$hist, freq=F, xlim=c(12, 120), ylim=c(0, 0.1),

    main=rownames(alpha)[j], xlab=expression(n[total]),

    cex.main=0.95, cex.axis=0.9, col=col, las=1)

  abline(v=c(res$nmean, res$nperc[["50%"]]), lty=c(1, 3))

  legend("topright", box.lty=0, legend=c("mean", "median"), lty=c(1, 3),

    cex=0.9)

}

close.screen(all.screens=T)

I luf open source!

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

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

Complete thread:

Does unequal alpha distribution make sense? Dr_Dan 2015-05-19 08:29
- Maybe; but watch the TIE! Helmut 2015-05-28 15:04
  - Advantages d_labes 2015-06-05 09:35
    - Advantages ElMaestro 2015-06-05 10:07
      - Advantages – performance measure d_labes 2015-06-05 11:21
        
        Advantages – performance measure Helmut 2015-06-05 13:29
        
        Advantages – performance measure d_labes 2015-06-05 21:27
        
        Advantages – performance measure Helmut 2015-06-05 23:29
        
        Histogram wonder d_labes 2015-06-06 12:58
        
        Histogram charlatanryHelmut 2015-06-09 13:43
        
        Histogram beauty d_labes 2015-06-09 14:55
        
        Histogram beast Helmut 2015-06-09 15:24
- Does unequal alpha distribution make sense? Dr_Dan 2015-05-29 08:33
  - Does unequal alpha distribution make sense? ElMaestro 2015-05-29 09:31
    - Does unequal alpha distribution make sense? nobody 2015-05-29 12:56
      - Old beliefs die hard Helmut 2015-05-29 13:27
        
        Old beliefs die hard nobody 2015-05-29 13:41
        
        Old beliefs die hard Helmut 2015-05-29 18:08
        
        Old beliefs die hard ElMaestro 2015-05-29 18:57
        
        Old beliefs die hard nobody 2015-05-29 20:06
        ♩ ♪♫♬`·.¸¸.·´`·.¸¸. Helmut 2015-06-02 01:52
        
        TSD only an option in exceptional cases Dr_Dan 2015-06-02 08:00
        
        TSD only an option in exceptional cases nobody 2015-06-02 09:23
        
        OT Helmut 2015-06-02 12:07
        
        OT nobody 2015-06-02 12:41
- Banana splits Helmut 2015-06-02 00:48