2/13/01

Dawn
Levy, News Service (650) 725-1944; e-mail: dawnlevy@stanford.edu

**Donoho tops list of most-cited
mathematical scientists**

Five Stanford statistics professors were among
the top 15 mathematical scientists cited during
the 1990s, according to *Science Citation Index*,
a publication of the Institute for Scientific
Information. David Donoho topped the list at 632
citations, followed by his frequent co-author
Iain Johnstone (3rd with 559 citations), Brad
Efron (11th with 382 citations), Jerome Friedman
(12th with 373 citations) and Robert Tibshirani
(14th with 356 citations). No other university's
mathematics, statistics or applied mathematics
department had more than two members listed.

A key reason the Stanford statisticians were
cited so often was the fact that their work
focused on useful methodology, Efron said:
"One of the nice recent turns in the field
of statistics, since 1970, is a greater interest
in algorithms that help scientists with difficult
data problems. This applies to most scientists
these days, since the computer age has allowed
much more ambitious data-collection methods. The
Stanford department has been the world leader in
this movement."

Joint appointments with other science
departments helped foster the development of
useful methodologies. Tibshirani, Johnstone and
Efron have appointments in the Health Research
and Policy Department of the School of Medicine,
and Friedman holds a joint appointment at the
Stanford Linear Accelerator Center.

To compile the list, editors of *Science
Citation Index* first identified the 200
most-cited papers for each year in the 1990s.
Then they counted individual citations for each
of the authors of the 2,000 identified papers.

Donoho and Johnstone have worked together on a
spectacularly successful series of papers
concerning wavelets -- modern versions of the
sine and cosine waves that mathematicians use to
tease out the signal from the noise to reveal the
structures of earthquakes, solar activity and
other cyclical phenomena. The Donoho-Johnstone
work helped make wavelets accessible for
statistical analysis.

Efron, the Max H. Stein Professor, is the
inventor of the "bootstrap," a general
computer-based way of attaching plus-or-minus
values to a statistical estimate (as in, for
example, "57 percent of the public plus or
minus 3 percent are in favor of subsidizing
public utilities"). Efron and Tibshirani
wrote a book on this topic in the '90s.

Friedman is co-inventor, with Stanford's
Richard Olshen and the University of
California-Berkeley's Charles Stone and Leo
Breiman, of CART. CART is a popular way of
generating the diagnostic trees used in medicine
and many other disciplines.

Tibshirani and Stanford colleague Trevor
Hastie invented a popular data-modeling method
called "generalized additive modeling."
They are currently working with Friedman on a
book on modern methods for data mining. These are
methods that can be applied to large complex data
sets such as those in the Human Genome Project.

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