## Questions and Ambiguities [BE/BA News]

Dear Helmut,

SAS has 5 different percentile definitions. The default is:

Let n*p=j+g where j is the integer part, g is the fractional part, n is the number of values, x the ordered values.

Let y denote the percentile. Then (SAS PCTLDEF=5)

This corresponds to R's Type 2 I think.

If the 'outlier' considerations based on the crippled EMA model makes any sense at all, which I'm not convinced at all , I would vote for an analysis of the residuals, not the period ratios also they appeared a natural choice on the first view.

Pro's:

To add more ambiguities:

❝ Period ratios (second / first administration):

❝ Type 3: SAS according to R-doc - 2 outliers (#46: 3.524, #45: 26.08)

❝ Type 5: or is this SAS? - 2 outliers

❝ Type 6: Minitab, SPSS, Phoenix/WinNonlin - 2 outliers

❝ ...

SAS has 5 different percentile definitions. The default is:

Let n*p=j+g where j is the integer part, g is the fractional part, n is the number of values, x the ordered values.

Let y denote the percentile. Then (SAS PCTLDEF=5)

```
y = 0.5*(x
```_{j}+x_{j+1}) if g=0

y = x_{j} if g>0

This corresponds to R's Type 2 I think.

❝ Don’t know what to do. Suggestions?

If the 'outlier' considerations based on the crippled EMA model makes any sense at all, which I'm not convinced at all , I would vote for an analysis of the residuals, not the period ratios also they appeared a natural choice on the first view.

Pro's:

- Period effects accounted for

- Analysis within the log domain (deemed necessary for AUC, Cmax)

- Distribution hopefully nearly normal, nearly symmetric because of the previous point, such that the 3xIQR rule can be applied reasonably

- Independent of order (first/second or second/first)

- Period effects different from the whole model, because of throwing away all data under Test, residuals therefore may be biased

- Residuals not independent because of the model fitted (2 values of residual on a subject only different in sign, must throw away 1/2 of them)

To add more ambiguities:

- simple residuals?
- studentized residuals?
- external studentized residuals (leave-one-out residuals)?

- other influence statistics (e.g. Cook's distance)?

—

Regards,

Detlew

Regards,

Detlew

### Complete thread:

- EMA BE-GL: Clarifications / Corrections? Helmut 2010-06-22 18:53 [BE/BA News]
- Good news!? d_labes 2010-06-23 10:09
- Good news!? Helmut 2010-06-23 10:11
- Update Helmut 2011-02-05 18:48
- Q&A published 14 March 2011 Helmut 2011-03-16 13:44
- Q&A published 14 March 2011 ElMaestro 2011-03-16 14:20
- Phoenix/WinNonlin 6.1.0.173 Helmut 2011-03-17 04:23
- ANOVA party prevails d_labes 2011-03-17 11:00
- THX! Helmut 2011-03-19 02:59
- Outlier d_labes 2011-03-24 11:55
- Outliers - yes, but how? Helmut 2011-03-24 15:09
- Questions and Ambiguitiesd_labes 2011-03-28 14:16
- Residuals and Outliers in Replicate Design Crossover Studies d_labes 2011-04-04 08:53

- Outliers - yes, but how? Helmut 2011-03-24 15:09
- Info requested ElMag 2011-03-24 12:45
- Confused as well... Helmut 2011-03-24 16:50

- Outlier d_labes 2011-03-24 11:55

- THX! Helmut 2011-03-19 02:59
- Q&A published 14 March 2011 Priyanka_S 2011-03-21 14:28
- SAS code: Warning d_labes 2011-03-21 16:08
- Copy & paste Helmut 2011-03-21 22:38
- Subtleties, flaws, questions d_labes 2011-03-22 09:24
- Subtleties, flaws, questions Helmut 2011-03-27 20:35
- Not estimable in the model The user 2017-03-14 10:16
- Not estimable in the model ElMaestro 2017-03-14 11:02
- Not estimable in the model The user 2017-03-14 12:13
- Not estimable in the model ElMaestro 2017-03-14 12:41

- Not estimable in the model The user 2017-03-14 12:13
- Not estimable in the model Helmut 2017-03-18 21:59
- Food not the same between groups Beholder 2021-11-10 14:35
- Food not the same between groups ElMaestro 2021-11-17 09:50

- Food not the same between groups Beholder 2021-11-10 14:35

- Not estimable in the model ElMaestro 2017-03-14 11:02

- Not estimable in the model The user 2017-03-14 10:16

- Subtleties, flaws, questions Helmut 2011-03-27 20:35

- Subtleties, flaws, questions d_labes 2011-03-22 09:24

- Copy & paste Helmut 2011-03-21 22:38

- SAS code: Warning d_labes 2011-03-21 16:08

- Q&A published 14 March 2011 Helmut 2011-03-16 13:44

- Update Helmut 2011-02-05 18:48

- Good news!? Helmut 2010-06-23 10:11

- Good news!? d_labes 2010-06-23 10:09