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BEBAC Ing. Helmut Schütz

Articles

This series of articles was inspired by recurring discussions in the Bio­equi­va­lence and Bio­avail­ability Forum and by questions I received from my clients or from re­gu­la­tory assessors.

The content expressed in the articles presents my purely personal opinions.
Even though regulatory requirements are largely taken into account, some of my firm convictions are based solely on scientific findings I have gained during my more than 45 years of work in this field, and by no means constitute a »cookbook approach« that should be followed uncritically. I do not make any representations or warranties regarding the accuracy of such content.

The true Enlightenment thinker, the true rationalist,
never wants to talk anyone into anything.
No, he does not even want to convince;
all the time he is aware that he may be wrong.
– Karl R. Popper

If most of the articles seem too focused on statistics, I apologize. This is due to my professional background, which has made it difficult for me to write engaging narratives.
To follow along with the examples in the articles, you will need and a few of its packages.

To the right articles are listed in chronological order. The articles are organized by topic below.

Consider activating JavaScript. Otherwise, you have to be proficient in reading LaTeX since formulas in the articles will not be rendered. Furthermore, the TOC in the left column for navigation will not be available and code-folding not supported. Sorry for the inconvenience.

A Short History of Bioequivalence  [2024-04-09, UPD 2026-05-28]
(especially recommended for beginners)

Power Calculation and Sample Size Estimation

Equivalence

Non-Inferiority/Superiority, Non-Superiority  [2022-07-24, UPD 2024-04-08]

Dose Proportionality 🚧

Prospective Power

Noncompartmental Analysis

Miscellaneous

Statistics

Design Issues

Software

Those people who think they know everything
are a great annoyance to those of us who do.
– Isaac Asimov

I have tried to cite online sources as much as possible in the articles. Others were published before the in­ter­net was developed. I have them on yellowed or even faint thermal paper of FAX [‼] ma­chines. Some books are out of print; you might be able to find them used. No, I will not sell any of them.
Contrary to us mere mortals who have to maintain a version control of documents, agen­cies don’t care. They change the structure of their websites (worst are the ones of the ANVISA and the WHO), don’t establish auto­ma­tic re­di­rects, rename or even delete files… In 2009 the FDA restructured its website with only a few redirects. Which made matters even worse: the ‘new’ pages have since disappeared altogether and are not even ar­chived. I’m a reviewer at the Wi­ki­pe­dia. It was a Sisyphean task to fix the more than 2,000 links acting as references in articles. Heck, we volunteers do that in our free time – THX, FDA logo!
Quod licet Iovi, non licet bovi
If you discover an error, please drop me a note at [email protected].

All articles are licensed under CC BY 4.0 Creative Commons Attribution 4.0 Helmut Schütz 2026.