Bioequivalence and Bioavailability Forum 04:54 CET

Main page Policy/Terms of Use Abbreviations Latest Posts

 Log in |  Register |  Search

Outliers - yes, but how? [BE/BA News]

posted by Helmut Homepage - Vienna, Austria, 2011-03-24 15:09  - Posting: # 6806
Views: 24,612

Dear D. Labes!

» This quote, or is it your own poetry, …

I borrowed it from a personal discussion page at Wikipedia.

» … is really google resistant. First time that I noticed the Net is not omniscient!

Well, personal discussion pages of WP are blocked from being indexed by Google. I have blocked some pages (i.e., the download section and the latest posts) from Google as well. Requires two lines in the domain’s robots.txt
User-agent: *
Disallow: /foo/

… and adding rel="nofollow" to respective links within other pages (the same is done here; look at the HTML code).

» » … Did you have a look at box plots and/or QQ-plots of residuals? What about subjects 45 and 52 (studentized residuals outside ±1.96 and outside 3×IQR)?
»
» Which residuals did you analyse? Which model? Please enlighten me.

I used EMA’s crippled model (test removed), Sequence+Subject(Sequence)+Period and threw away one period’s residuals (same values, but different in signs to the respective other one).

» What do you think: which type of boxplot should we apply? Best for our sponsors would be a simple boxplot with whiskers up to minimum/maximum not showing any 'outlier' :-D.

:rotfl:

I have chosen ±3×IQR following the convention (!) that values within 1.5-3×IQR are ‘mild’ outliers and outside 3×IQR are ‘severe’ outliers. I’m exploring full replicate data-sets right now – outliers almost in all of them. Don’t know whether residuals make any sense at all (see also this post: period ratios instead?). I would end up with different numbers of outliers, depending on the method of calculation of the IQR (see R-manual). 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
Type 7: default in S, R - 3 outliers (as above + #13: 3.349)

                               CVWR    Scaled  AR      width
Full data set:                 47.0  71.23 - 140.40    69.17
#45, #52 excluded (residuals): 32.2  78.79 - 126.93    48.14
#45, #46 excluded (ratios):    35.3  77.08 - 129.73    52.65


Don’t know what to do. :confused: Suggestions?
Maybe Q&A is an abbreviation for Questions and Ambiguities.

Cheers,
Helmut Schütz
[image]

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

Complete thread:

Activity
 Mix view
Bioequivalence and Bioavailability Forum |  Admin contact
19,154 posts in 4,080 threads, 1,308 registered users;
online 20 (0 registered, 20 guests [including 11 identified bots]).

One can show the following: given any rule, however “fundamental”
or “necessary” for science, there are always circumstances
when it is advisable not only to ignore the rule,
but to adopt its opposite.    Paul Feyerabend

The BIOEQUIVALENCE / BIOAVAILABILITY FORUM is hosted by
BEBAC Ing. Helmut Schütz
HTML5 RSS Feed