Webinar 1
Stratified Analyses: Tips for Improving Power
Devan V. Mehrotra (Merck Research Laboratories)
October 21, 2008, Noon-2:00 PM (Eastern time)
The Mantel-Haenszel test and the van Elteren test, both implemented in
SAS PROC FREQ, are widely used for stratified analyses of binary and ranked
data, respectively. Both methods have good power properties, but only under
certain restrictive assumptions; when the assumptions are violated, there
can be a notable loss in power. In this tutorial, we will describe some
alternatives to these popular methods, including the "minimum risk" weighting
strategy for stratified binary data and an "adaptive" testing
strategy for stratified rank-based analyses. We will use simulations to
provide guidance on which methods might be more appropriate under given
conditions. Numerical examples will be used throughout for illustration,
and to reinforce the key points

Webinar 2
Bioequivalence
Scott Patterson (Wyeth) and Byron Jones (Pfizer)
December 10, 2008, 10:00-Noon PM (Eastern time)
This introductory course will focus on the design and analysis of bioequivalence
studies for orally administered drug products. It provides a detailed
overview of the most well-established method of demonstrating bioequivalence.
The
following topic will be covered:
1. Drug development, clinical pharmacology and statistics.
2. History and international bioequivalence regulations.
3. 2x2 cross-over designs and average Bioequivalence with examples.
The course offers a well-balanced mix of theory and applications, including
regulatory considerations. Examples from real trials are used throughout
the discussion to illustrate the statistical approaches discussed in the
course. Software implementation of the described statistical methods may
be found at http://www.crcpress.com/e_products/downloads/download.asp?cat_no=C5300.
Text
book
Patterson S, Jones B. (2006). Bioequivalence and Statistics in Clinical
Pharmacology (Chapters 1-2). Chapman and Hall, CRC Press, London.

Webinar
3
Classical sample-size analysis for hypothesis testing (Part I)
Ralph O'Brien (Case Western)
January 29, 2009, Noon-2:00 PM (Eastern time)
This session will cover the key concepts, all by discussing a straightforward,
realistic, two-arm clinical trial being planned to test a fictional
lactate-lowering drug (QCA) that promises to reduce mortality in
children with severe malaria.
We will first discuss that if QCA has no effect, the distribution
of the p-value is uniform between 0.00 to 1.00, regardless of how
large
the total
sample size (N) is, a concept misunderstood by many who think that
p-values shift towards 1.00 when the null hypothesis is true. The
graphs let
us see that under the null hypothesis, Prob[p
a]
= a, the Type I error rate.
Then I show how the p-value shifts more towards 0.00 when QCA is
conjectured to be more effective and how this leftward shift increases
when N
increases and when N is allocated in a nearly balanced manner between
the two
arms.
This lets us see graphically the Type II error rate, Prob[p > a]
= ß, and the power = Prob[p
a]
= 1 - ß. Time will be devoted to discussing
how one formulates the scenarios for a typical sample-size analysis
and how one presents the results of this exercise in a statistical
considerations
section in a research proposal. We will cover some of the messy
issues that arise, such as: Are sample-size analyses relevant for “pilot” studies?
How do we deal with the built-in trade-off between a and ß In
other words, what are a prudent a and an acceptable power? How does
using
a one-sided
versus two-sided hypotheses affect these matters? What is “statistical
gaming” in sample-size analysis?
Text book
O’Brien R, Castelloe J. (2007). Sample-size analysis for traditional
hypothesis testing: Concepts and issues. Pharmaceutical Statistics Using
SAS: A Practical Guide. Dmitrienko A, Chuang-Stein C, D’Agostino
R. (editors). SAS Press: Cary, NC.

Webinar 4
Classical sample-size analysis for hypothesis testing (Part II)
Ralph O'Brien (Case Western)
February 12, 2009, Noon-2:00 PM (Eastern time)
This session will quickly review the essentials of the first session
and then continue with the malaria example to explore more vital
questions that classical sample-size analyses fails to address.
That is, if
the planned
study yields a significant p-value, what is the chance this
is a Type I error? Likewise, if the study turns out non-significant,
what
is
the chance
this is a Type II error? By using judgments about the probability
that the null hypothesis is false, we apply Bayes Theorem (taught
with simple
calculations
in a table, no formulas) to assess these “crucial” Type I and
II error rates, and we show (using a simple a Excel program) that they can
differ greatly from their classical counterparts. Importantly, both crucial
error rates are reduced by increasing the statistical power. Studies with
small N that propose to test speculative hypotheses are prone to large crucial
error rates. The final phase of the session deals with an actual early trial
of a highly novel treatment for atherosclerosis in which a 0.02 p-value
was deemed to be “the first convincing demonstration” of
efficacy. What the investigators failed to understand, however,
is that their crucial
Type I error rate may have been well over 85%. We will end by
going though a mock study planning exercise to design the follow-up
study.
Text book
O’Brien R, Castelloe J. (2007). Sample-size analysis for traditional
hypothesis testing: Concepts and issues. Pharmaceutical Statistics Using
SAS: A Practical Guide. Dmitrienko A, Chuang-Stein C, D’Agostino
R. (editors). SAS Press: Cary, NC.

About Webinars
A webinar is a seminar which is conducted over the World Wide Web.
It is a type of web conferencing. In contrast to a Webcast, which is transmission
of information in one direction only, webinars are designed to be interactive
between the presenter and audience. A webinar is 'live' in the sense that
information is conveyed according to an agenda, with a starting and ending
time. In the case of the Biopharmaceutical Section Webinar Series, the presenter
speaks over a standard telephone line, pointing out information being presented
on screen. The audience can respond via a chat feature. The word 'webinar'
is a blend of web and seminar.
System Requirements
Operating System: Windows 2000 to present, Macintosh OSX, Linux Redhat
Browser: Internet Explorer (IE) 5.5+, Firefox 2.0+, Opera
9.0+, Mozilla 1.71+, Safari 3.1
Other: Events with streaming audio or video require Macromedia Flash 8.0+
Hardware: 56Kbps Internet access. Speakers or headphones and cable modem,
DSL, ISDN, or equivalent broadband needed to receive audio/video streaming
(128K minimum).
*Opera browser will not allow access to the Question and Answer feature
of the console.
More information on the Web-based training program can be found at the biopharmaceutical
network's web site.