Bioequivalence and Bioavailability Forum

log to 3 decimals guess work [🇷 for BE/BA]

posted by d_labes  – Berlin, Germany, 2010-05-05 18:00 (5526 d 18:38 ago) – Posting: # 5301
Views: 24,974

Dear Yung-jin,

❝ ❝ BTW: I question your results! Full match of the results with log to full precision or with log rounded to 3 digits (after dec. separator), respectively, in the ANOVA's and the CI's up to the last printed digits has a probability of very near to zero.

❝

❝ Yes, it is possible, but most of time (I think) are unlikely. The transformed from original data, such as Cmax and AUCs, are done under R, not manually. That's why it makes no difference, because both transformations are done by the same machine under R. It could be different when comparing between different machines, such as a 32-bit vs. a 64-bit machine, or between different OS.

Totally confused .

You have described in your original post that you compared

❝ ... the runs between the pre-transformed

❝ manually Cmax to 3 digits and internally transformed with the model

❝ (lnCmax<- lm(log(Cmax) ~ seq + subj:seq + prd + drug , data=TotalData))

(emphasis by me)

I guess that you compared the logs calculated to full precision
TotalData$lnCmax <- log(TotalData$Cmax)
lm(lnCmax ~ seq + subj:seq + prd + drug, data=TotalData)
versus my suggestion
lm(log(Cmax) ~ seq + subj:seq + prd + drug, data=TotalData).

To get Helmut's concern change
TotalData$lnCmax <- round(log(TotalData$Cmax),3)
or even more drastically round to 2 decimals.

Complete thread:

• F value for sequence effect Pakawadee 2010-05-03 11:48 
  • F value for sequence effect AA 2010-05-03 13:38
  • F value for sequence effect Ohlbe 2010-05-03 14:16
    • F value for sequence effect Pakawadee 2010-05-04 03:48
      • F value for sequence effect ElMaestro 2010-05-04 08:48
        • F value for sequence effect Pakawadee 2010-05-04 12:12
        • F value; rounding Helmut 2010-05-04 13:00
          • log rounding machine d_labes 2010-05-04 13:35
          • Rounding or not to rounding yjlee168 2010-05-04 21:27
            • Rounding or not to rounding ElMaestro 2010-05-04 23:23
              • Rounding or not to rounding yjlee168 2010-05-05 01:17
                • Rounding or not to rounding ElMaestro 2010-05-05 12:15
                  • Rounding or not to rounding yjlee168 2010-05-05 12:59
                    • Rounding or not to rounding ElMaestro 2010-05-05 13:15
                      • Rounding or not to rounding yjlee168 2010-05-05 13:28
                      • Type III SS sequence effect -revised yjlee168 2010-05-05 23:58
                        • Type III SS sequence effect -revised ElMaestro 2010-05-06 07:27
                          • SAS-like Type III SS sequence with bear? yjlee168 2010-06-03 13:04
            • New dataset? d_labes 2010-05-05 11:40
              • New dataset? yjlee168 2010-05-05 12:31
                • log to 3 decimals guess workd_labes 2010-05-05 16:00
                  • log to 3 decimals guess work yjlee168 2010-05-05 20:13
                    • rounding and presentation of data Helmut 2010-05-05 20:29
                      • rounding and presentation of data yjlee168 2010-05-05 21:05
                        • rounding and presentation of data in R martin 2010-05-06 07:53
                      • Canadian logs d_labes 2010-05-06 10:12
                        • Canadian logs ElMaestro 2010-05-06 10:21
                        • Canadian logs Helmut 2010-05-06 14:57
                          • Canadian lost d_labes 2010-05-06 15:38