Clinical Impact Beyond 'Time to First' Analyses

Posted by Esha Senchaudhuri

Oct 21, 2014 9:00:00 AM

Every year, the East Users Group Meeting brings together notable experts from industry and academia to discuss the future of biostatistical advances in clinical trials, as well as the role of software in facilitating these breakthroughs. In honor of this year’s event, which will be taking place at the Loews Hotel in Philadelphia on October 22, the Cytel Blog will spend the next couple of weeks providing glimpses into the range of discussion presented at the EUGM table.

One debate that has already received quite some attention, involves the weighting of various morbidities in studies with composite endpoints. In a 2013 editorial in the European Heart Journal of the European Society of Cardiology, EUGM speaker Professor L.J. Wei and his colleagues wrote, "A reported P-value must not be confused with an assessment of the magnitude of a treatment's effect in a way that is meaningful to the patient, the clinician and the regulator." [1]

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Topics: East, East 6.3, Statistical Programming, Statistical Puzzles, Statistical Analysis, Cardiovascular

2014 Zelen Award Honors Statistician and Educator

Posted by Esha Senchaudhuri

May 29, 2014 9:58:00 AM

Cytel has taken the initiative to train the next generation of clinical programmers through its innovative Clinnical Programming Laboratory [see Cytel's CliPLab].

What about training the next generation of statisticians? The Harvard School of Public Health has just awarded the 2014 Marvin Zelen Leadership Award in Statistical Sciences to a distinguished statistician and educator. 

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Topics: Marvin Zelen, Training and Education, Statistical Puzzles

StatXact 25th Anniversary: A Horizon for the Stars

Posted by Esha Senchaudhuri

Apr 21, 2014 3:57:00 PM

The core methodological problem that would eventually spur the development of Cytel’s StatXact software was first posed by Harvard’s Marvin Zelen at a computational seminar in the late 1970s. Zelen, a distinguished professor of statistical sciences and head of the Department of Biostatistics at Harvard University, was also serving as the Director of the Dana Farber Cancer Institute.

The analysis of serious adverse events from cytotoxic agents in oncology trials were heavily dependent on an imprecise Cochran rule to measure the signifincance of small sample categorical data. The crude calculation meant that estimations of p-values were wide off the mark. Zelen challenged his students to find ways to expand Fisher’s exact test to r x c contingency tables, and by doing so to seal the promise of more effective development and delivery of urgent cancer treatments.

Cyrus Mehta and Nitin Patel took up Zelen’s challenge, publishing a series of papers on exact significance testing throughout the 1980s. Despite offering novel statistical solutions to persisting problems, the implementation of such solutions clearly required assistance from software. Unfortunately, few venture capitalists were willing to invest in a package of arcane statistical tests that were largely still in development.

Cytel was created with a grant from the National Cancer Institute, with a view to developing software that would make newer exact tests widely available for clinical studies. Its first software package, StatXact, is now used for exact testing in oncology, as well as environmental studies, public health, demography, law, and several areas of medicine and clinical development. The widespread use of exact tests has led to an array of intriguing research questions involving the power of various exact tests. Below we present a favorite finding, on the power of conditional versus unconditional exact tests:

Mehta, Cyrus R., and Pralay Senchaudhuri. "Conditional versus unconditional exact tests for comparing two binomials." Cytel Software corporation 675 (2003).


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Topics: StatXact, Nitin Patel, Cyrus Mehta, White Paper, Statistics Article full PDF, Oncology, Access to Paper PDF, Exact Tests, Marvin Zelen, Statistical Puzzles

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