#  Devin Caughey (Workshop in Applied Statistics) 

 



####  calendar\_today Date and Time 

 **February 19, 2025** 

 12:00PM - 01:30PM EST 

####  pin\_drop Location 

 **CGIS Knafel room K354, or virtual via Zoom**  



 

 



 

##  Today's Speaker

 Devin Caughey (MIT), "MODGIRT: Multidimensional Dynamic Scaling of Aggregate Survey Data"

##  Abstract

 Dynamic models of aggregate public opinion are increasingly popular, but to date they have been restricted to unidimensional latent traits. This is problematic because in many domains the structure of mass preferences is multidimensional. We address this limitation by deriving a multidimensional ordinal dynamic group-level item response theory (MODGIRT) model. We describe the Bayesian estimation of the model and describe a novel workflow for dealing with the tricky problem of identification. With simulations, we show that MODGIRT recovers aggregate parameters without estimating subject-level ideal points and is robust to moderate violations of assumptions. We further validate the model by reproducing at the group level an existing individual-level analysis of British attitudes towards redistribution. We then reanalyze a recent cross-national application of a group-level IRT model, replacing its domain-specific confirmatory approach with an exploratory MODGIRT model. We describe extensions to allow for overdispersion, differential item functioning, and group-level predictors. A publicly available R package implements these methods.

 *The Applied Statistics Workshop (Gov 3009) meets all academic year, Wednesdays, 12pm-1:30pm, in CGIS K354. This workshop is a forum for advanced graduate students, faculty, and visiting scholars to present and discuss methodological or empirical work in progress in an interdisciplinary setting. The workshop features a tour of Harvard's statistical innovations and applications with weekly stops in different fields and disciplines and includes occasional presentations by invited speakers.  
  
All interested Harvard affiliates are invited to attend.*



 

 



 

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