This week's speaker at the Gov 3009 seminar is Donna Spiegelman, of the
Departments of Epidemiology and Biostatistics, Harvard School of Public
Health. She will be speaking on "Correlated errors in biased surrogates:
study designs and methods for measurement error correction."
Abstract:
The measurement error model proposed by Kipnis, et al. (1999) allows for
correlations between subject-specific biases and between random
within-subject errors in the surrogates obtained from two modes of
measurement. However, most of these model parameters are not identifiable
from the standard validation study design, including, importantly, the
attenuation factor needed to correct for bias in relative risk estimates
due to measurement error using the method of regression calibration
(Rosner et al., 1989). We propose validation study designs that permit
estimation and inference for the attenuation factor and other parameters
of interest when this model applies. We use an estimating equations
framework to develop semi-parametric estimators for these parameters,
exploiting instrumental variables techniques. The methods are illustrated
through application to data from the Nurses' Health Study (Willet et al.,
1992) and Health Professionals' Follow-up Study (Grobbee et al., 1990) and
comparisons are made to simpler models.
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 seminar is Mark Glickman, speaking on
"Combining Speed and Accuracy to Assess Error-free Cognitive
Processes."
The paper can be found at: http://math.bu.edu/people/mg/papers/spacc.ps,
and an abstract follows. More information on the seminar can be found
below.
Abstract:
Many experiments on human cognition involve having a subject
make a judgment as quickly and accurately as possible. Both reaction times
and error rates are widely used indices of human performance in such
experiments. A difficulty in relying on either one of these indices alone
is the problem of a speed/accuracy tradeoff; subjects who react quickly
are more likely to have higher error rates, whereas subjects who are more
accurate are likely to have slower reaction times. Another difficulty
arises when subjects respond slowly and inaccurately (rather than quickly
but inaccurately), e.g., due to a lapse of attention. We introduce an
approach that combines response time and accuracy information that
addresses both situations. The modeling framework assumes two latent
competing processes. The first, the error-free process, always produces
correct responses. The second, the residual process, results in all
observed errors and some of the correct responses (but does so via
non-specific processes, such as guessing in compliance with instructions
to respond on each trial). Inferential summaries of the speed of the
error-free process provide a principled assessment of cognitive
performance reducing the influences of both fast and slow guesses.
Likelihood analysis is discussed for the basic model and extensions. This
is joint work with Jeremy Gray (Washington Univ in St. Louis), and Carlos
Morales (Worcester Polytechnic Institute).
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 seminar is James Fowler, speaking on
"Connecting the Dots: How Do We Impute the Structure and Content of Large
Social Networks?"
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 seminar is Gary King, speaking on
"Enhancing the Validity and Cross-cultural Comparability of Survey
Research."
The full paper can be found at:
http://gking.harvard.edu/preprints.shtml#vign
Abstract: We offer a new approach to writing survey questions and a new
statistical model that together at least partially ameliorate two
long-standing problems in survey research. The first is how to
measure complicated concepts, such as freedom, health, political
efficacy, pornography, etc., that researchers know how to define
clearly only with reference to examples. The second problem is when
different respondents interpret identical survey questions in
incomparable ways, as can occur when comparing respondents in
different countries speaking different languages, but it also occurs
frequently with different groups in the same country. Our approach
to these problems is to ask respondents for self-assessments of the
concept being measured along with assessments, on the same scale, of
each of several hypothetical individuals described by short
vignettes. The actual (but not necessarily reported) levels for the
people in the vignettes are, by the design of the survey, invariant
over respondents and thus provide anchors for our statistical model
to transform the self-assessments to a comparable scale. With
analysis, simulations, and real surveys in several countries, we
show how ignoring these problems can lead to the wrong substantive
conclusions and how our approach can fix them. Our methods build on
insights from application-specific research on voters and
legislators in political science to produce a more general
measurement device. You may also be interested in the Anchoring
Vignettes web site, http://gking.harvard.edu/vign/, which includes
information about conferences on the subject, a FAQ, software,
example vignettes, and other materials.) This is joint work with
Christopher J.L. Murray, Joshua A. Salomon, and Ajay Tandon.
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
