Hi all,
Our next virtual meeting will be at 12pm (EST) Wednesday, March 10, where
Adeline Lo (University of Wisconsin-Madison) presents research on
"Mixed-Membership Stochastic Blockmodels for Bipartite Networks:
Application to Cosponsorship in the US Senate."
*Abstract*:
Many networks in political and social research are naturally bipartite —
with two distinct types of actors (nodes), and edges connecting exclusively
across the actor types. An example of such networks is the one that results
from cosponsorship decisions, in which legislators are connected to the
bills they support. Typically, researchers who wish to study these networks
are forced to "project" or marginalize over one node type, in an effort to
form the kinds of unipartite networks that standard models can handle. This
can result in aggregation bias and loss of relevant information about the
node type that is averaged over. To avoid these issues, we propose an
extension of the mixed-membership stochastic blockmodel that operates
directly on the bipartite network structure, incorporating both node and
dyad-level covariates. We design and implement a fast, scalable stochastic
variational algorithm to obtain estimates of latent variables and
hyper-parameters, and illustrate our model using data from the 107th and
108th sessions of the U.S. Senate. We find that using our model allows us
to uncover interesting groups of bills, explore the effects of individual
ideology on the likelihood of bipartisan cosponsorship, and evaluate the
norms of reciprocity in the legislative context.
*Zoom link*:
https://harvard.zoom.us/j/97787602526?pwd=Uzh3bVVVS0F4TEVYQTJlV3BQNjcydz09
*Schedule of the workshop*:
https://projects.iq.harvard.edu/applied.stats.workshop-gov3009
Looking forward to seeing you all on Wednesday!
Best,
Soichiro
--
Soichiro Yamauchi
PhD candidate
Harvard University
URL:
https://soichiroy.github.io/