  In this study, we propose a new index for measuring excellence in science
which is based on collaborations (co-authorship distances) in science. The
index is based on the Erd\H{o}s number - a number that was introduced several
years ago. We propose to focus with the new index on laureates of prestigious
prizes in a certain field and to measure co-authorship distances between the
laureates and other scientists. To exemplify and explain our proposal, we
computed the proposed index in the field of quantitative science studies
(PWIPM). The Derek de Solla Price Memorial Award (Price Medal, PM) is awarded
to outstanding scientists in the field. We tested the convergent validity of
the PWIPM. We were interested whether the indicator is related to an
established bibliometric indicator: P(top 10%). The results show that the
coefficients for the correlation between PWIPM and P(top 10%) are high (in
cases when a sufficient number of papers have been considered for a reliable
assessment of performance). Therefore, measured by an established indicator for
research excellence, the new PWI indicator seems to be convergently valid and,
therefore, might be a possible alternative for established (bibliometric)
indicators - with a focus on prizes.
