This week's speaker at the Gov 3009 workshop is Lee Fleming from Harvard
Business School. He will be speaking on "Small Worlds Enhance
Innovation." This will be the final meeting of the year.
Abstract:
We'll first describe our data set of the collaboration networks of 2.1
million inventors from the last 30 years. We'll then present a short
paper that looks at the influence of small world networks and indirect
ties upon regional productivity (ie., is Silicon Valley really different
than Boston and does it matter). Finally, we'll sketch a preliminary
research design for doing analysis at the individual inventor level and
open it up to a discussion of the potential and problems at this level of
analysis. This is joint work with Charles King III and Adam Juda.
The paper is available at:
http://www.courses.fas.harvard.edu/~gov3009/handouts/SmallWorldEnhanceInnov…
Seminar Information:
The seminar meets at noon in Room 22, Center for Basic Research
in Social Sciences (CBRSS, 34 Kirkland St., this is the yellow building
across the street from William James Hall). Contact information, previous
presentations, and the spring schedule may be found at the course web
site: http://www.courses.fas.harvard.edu/~gov3009/. Lunch is provided.
To join the gov3009 mailing list, send e-mail to
gov3009-l-request(a)fas.harvard.edu with the following text message:
subscribe
end
Questions? Please contact the workshop coordinator, Liz Stuart, at
stuart(a)stat.harvard.edu
This week's speaker at the Gov 3009 workshop is Elizabeth Stuart from the
Department of Statistics. She will be speaking on
"Matching and the Use of Multiple Control Groups in the Context of Causal
Inference."
Abstract:
In observational studies, it is desirable to reduce bias due to
covariates by obtaining treated and control groups with similar
distributions of the covariates. This is often done by choosing well
matched samples of the original treated and control groups. However,
sometimes the originally chosen control units cannot provide adequate
matches for the treated units. In these cases, it may be desirable to
obtain matched controls from two control groups. Multiple control groups
have been used in the context of causal inference to test for hidden
biases; however, little work has been done on their use in matching or
adjustment for these biases. In this talk, we address two issues
associated with the use of multiple control groups. The first relates to
longitudinal data and the necessity to define ``baseline" for
non-randomized control units. This will be discussed in the context of a
randomized clinical trial for a drug that may become commercially
available, thus invalidating the traditional use of the control group.
Historical data on patients with the disease will be used to supplement
the original randomized control group. The second issue discussed will be
how to quantify differences in unobserved variables between multiple
control groups. Quantifying this bias can help guide the use of multiple
control groups. This topic will be discussed in the context of the
evaluation of a school-wide dropout prevention program where students in
the original treated and control schools were significantly different from
one another. The method explores the use of external national data on high
school students in addition to the local control students.
This is work in progress; no paper is available.
Seminar Information:
The seminar meets at noon in Room 22, Center for Basic Research
in Social Sciences (CBRSS, 34 Kirkland St., this is the yellow building
across the street from William James Hall). Contact information, previous
presentations, and the spring schedule may be found at the course web
site: http://www.courses.fas.harvard.edu/~gov3009/. Lunch is provided.
To join the gov3009 mailing list, send e-mail to
gov3009-l-request(a)fas.harvard.edu with the following text message:
subscribe
end
Questions? Please contact the workshop coordinator, Liz Stuart, at
stuart(a)stat.harvard.edu
This week's speaker at the Gov 3009 workshop is Jasjeet Sekhon from the
Government Department. He will be speaking on "Robust Estimation and
Outlier Detection for Overdispersed Multinomial Models of Count Data."
The full paper can be found at:
http://elections.fas.harvard.edu/election2000/MebaneSekhon.multinom.pdf
Abstract:
We develop a robust estimator---the hyperbolic tangent (tanh)
estimator---for overdispersed multinomial regression models of count
data. The tanh estimator provides accurate estimates and reliable
inferences even when the specified model is not good for an unknown
minority of the data. Seriously ill-fitted counts---outliers---are
identified as part of the estimation. A Monte Carlo sampling
experiment shows that the tanh estimator produces good results at
practical sample sizes even when ten percent of the data are
generated by a significantly different process. Theoretical results
suggest that asymptotically the estimator will produce good results
when up to half of the data are contaminated. The experiment shows
that, with contaminated data, estimation fails using four other
estimators: the nonrobust maximum likelihood estimator, the additive
logistic model and two SUR models. Using the tanh estimator to
analyze data from Florida for the 2000 presidential election matches
well-known features of the election that the other four estimators
fail to capture. In an analysis of data from the 1993 Polish
parliamentary election, the tanh estimator gives sharper inferences
than does a previously proposed heteroscedastic SUR model.
Seminar Information:
The seminar meets at noon in Room 22, Center for Basic Research
in Social Sciences (CBRSS, 34 Kirkland St., this is the yellow building
across the street from William James Hall). Contact information, previous
presentations, and the spring schedule may be found at the course web
site: http://www.courses.fas.harvard.edu/~gov3009/. Lunch is provided.
To join the gov3009 mailing list, send e-mail to
gov3009-l-request(a)fas.harvard.edu with the following text message:
subscribe
end
Questions? Please contact the workshop coordinator, Liz Stuart, at
stuart(a)stat.harvard.edu
This week's speaker at the Gov 3009 workshop is Tao Li from
the Government Department. He will be speaking on "Legislative Rule
Selection: a Study about US House of Representatives."
Some preliminary results will be presented, and further ideas discussed.
Seminar Information:
The seminar meets at noon in Room 22, Center for Basic Research
in Social Sciences (CBRSS, 34 Kirkland St., this is the yellow building
across the street from William James Hall). Contact information, previous
presentations, and the spring schedule may be found at the course web
site: http://www.courses.fas.harvard.edu/~gov3009/. Lunch is provided.
To join the gov3009 mailing list, send e-mail to
gov3009-l-request(a)fas.harvard.edu with the following text message:
subscribe
end
Questions? Please contact the workshop coordinator, Liz Stuart, at
stuart(a)stat.harvard.edu
