iiinova — where your digital self keeps evolving

shira mitchell @shiraamitchell.bsky.social · 07/10/2026

blog post: 2 different uses of simulated data 1. Simulated data to learn about the external world. 2. Simulated data to understand how a model works

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shira mitchell @shiraamitchell.bsky.social · 30/09/2026

blog post: ANOVA follow-up The classical ANalysis Of VAriance table (Sum Sq, Mean Sq, F statistic, p-value) tests whether batches of effects are zero V(beta_j) = 0. But it doesn't directly show estimated variances V(beta_j).

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shira mitchell @shiraamitchell.bsky.social · 23/09/2026

blog post: Fat Bear Week 2026 Happy Fat Bear Week to all who celebrate 🐻🎉 If estimating the bears' total size: under which outcome model does a Horvitz-Thompson (inverse probability) estimator do well ?

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shira mitchell @shiraamitchell.bsky.social · 16/09/2026

blog post: ANOVA Andrew says "Anova is still important; it’s just been subsumed by hierarchical models." How does ANOVA relate to Survey Statistics ?

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shira mitchell @shiraamitchell.bsky.social · 09/09/2026

blog post: @pewresearch.org finds “No Easy Fix for Bogus Respondents in Online Opt-In Polls” They try 3 screening methods and compare them with 3 data quality measures. How does screening affect estimates of 2024 vote choice ? How do opt-in and probability samples compare ?

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shira mitchell @shiraamitchell.bsky.social · 02/09/2026

blog post: logit shift and raking a short post to see the logit shift as a special case of raking

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shira mitchell @shiraamitchell.bsky.social · 26/08/2026

blog post: more on SynthMargins and Bayes-Raking We want to poststratify (MRP) but only have partial information (margins) about the poststratification variables in the population. More ideas from Bob Carpenter (in #mcmc_stan), @yajuansi.bsky.social, and @shirokuriwaki.bsky.social

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shira mitchell @shiraamitchell.bsky.social · 19/08/2026

blog post: Modeling Complex Contingency Tables We want to poststratify (MRP) but only have partial information about the poststratification variables in the population. Max Goplerud, @shirokuriwaki.bsky.social, Jens Wiederspohn, @adamcs.bsky.social, and Philip Greengard have ideas !

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shira mitchell @shiraamitchell.bsky.social · 12/08/2026

blog post: wanting workflow We review a covid survey case study from the new Bayesian Workflow book. We model: - measurement: test sensitivity and specificity - representation: differences between sample and population (MRP) How can workflow help us here ?

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shira mitchell @shiraamitchell.bsky.social · 05/08/2026

blog post: structured MRP to smooth survey weights Adjusting for lots of variables can lead to very large weights. So @yajuansi.bsky.social, @trangucc.bsky.social, Jonah Sol Gabry, and Andrew Gelman turned to a structured MRP and its equivalent weights.

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shira mitchell @shiraamitchell.bsky.social · 28/07/2026

blog post: equivalent models, equivalent weights (locally) with survey-weighting methods, we can ask: under which outcome models do they do well ? with outcome-model methods (like MRP), we can ask: what are the (locally) equivalent weights ?

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shira mitchell @shiraamitchell.bsky.social · 22/07/2026

blog post: poststratification without population level information Poststratification uses population data on X to help estimate a population mean E(Y). But sometimes population data on X isn't available: In 2016 Andrew asked pollsters to poststratify on party ID, but how ?

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shira mitchell @shiraamitchell.bsky.social · 17/07/2026

I stayed there the night before starting my section too ! It’s amazingly rebuilt post Helene. (Bridge still out tho, as you know.) I went from there NOBO for a week timed to end at Trail Days in Damascus.

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shira mitchell @shiraamitchell.bsky.social · 17/07/2026

I don't think the authors propose asking a different survey question. They focus instead on advocating for reporting statistical uncertainty as posterior win probabilities. CC @evanrosenman.bsky.social

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shira mitchell @shiraamitchell.bsky.social · 17/07/2026

Yes, with small samples and small true preference margins, in both the first round and runoff rounds we can easily land on the wrong side of the decision boundaries that determine the RCV winner.

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shira mitchell @shiraamitchell.bsky.social · 17/07/2026

This stuff is hard to understand, Chris !

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shira mitchell @shiraamitchell.bsky.social · 17/07/2026

happy trails ! I just did this section in May, it's magical.

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shira mitchell @shiraamitchell.bsky.social · 14/07/2026

blog post: quantifying uncertainty in ranked choice voting polls RCV uses rankings to get a winner by instant runoff. Polls estimate rank probabilities with uncertainty. Unlike with non-RCV, even in random samples a plurality of uncertainty mass can get an incorrect winner.

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shira mitchell @shiraamitchell.bsky.social · 08/07/2026

blog post: toy example for energy balancing weights How do energy balancing weights (used now by the NYT/Siena Poll) handle unsampled population groups ? Let's work thru a toy example and compare to Poststratification, Raking, and MRP.

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shira mitchell @shiraamitchell.bsky.social · 02/07/2026

blog post: Big Changes in the Times/Siena Poll 2 changes to their survey weights: 1. new weighting variable: support score 2. new weighting method: energy balancing

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shira mitchell @shiraamitchell.bsky.social · 24/06/2026

blog post: perfect collinearity in the sample but not in the population Two variables are perfectly collinear in your sample, so you drop one. You use your model to predict in the population. What can go wrong ? Let's talk thru a Census Bureau toy example from BDA2.

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shira mitchell @shiraamitchell.bsky.social · 17/06/2026

blog post: using MRP in later analyses (pride edition) happy pride ! 🌈 @jeffreylax.bsky.social & Phillips 2009 used MRP to estimate state-level public opinion about policies affecting gays and lesbians. They then use this as a predictor of whether the state adopts the policies.

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shira mitchell @shiraamitchell.bsky.social · 10/06/2026

blog post: should MRP workflow include LOCO-CV ? Individual-level loss orders models differently than the population-level loss we want judging MRP. To get population-level loss, use out-of-sample classical poststratification to compare with MRP. How to split data ? LOCO = leave one cell out.

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shira mitchell @shiraamitchell.bsky.social · 03/06/2026

🤩🥰 what a dream to get comments from you, let alone co-authoring a book !

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shira mitchell @shiraamitchell.bsky.social · 03/06/2026

blog post: it is (still) the people Survey Statistics blog series' 1st birthday 🥳 Andrew Gelman's 60-ish Birthday 🥳 and NYT weights with synthetic past vote 🗳️

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shira mitchell @shiraamitchell.bsky.social · 27/05/2026

blog post: double-plus robustness Meng (2022): GREG is not only “double robust” (consistent if either the outcome model or response model are correct), but “double-plus robust” (consistent if what is left of the outcome model and response model are uncorrelated).

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shira mitchell @shiraamitchell.bsky.social · 20/05/2026

blog post: GREG GREG is Generalized REGression estimator. We can think of it either as: 1. Adjusting an estimate based on the model with a Horvitz-Thompson estimate of the error, or 2. On the flip side, adjusting the Horvitz-Thompson estimate with the model.

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shira mitchell @shiraamitchell.bsky.social · 15/05/2026

blog post: relevant alternatives ? We saw that the multinomial logit model implies independence from irrelevant alternatives (IIA). Let’s expand the model to include choice set C within the logits f(X_ic,C), allowing for non-IIA.

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Reposted by shira mitchell

shira mitchell @shiraamitchell.bsky.social · 10/03/2026

blog post: work with us at Blue Rose ! use cutting edge statistics, machine learning, and engineering to study public opinion, forecast elections, and advise Democrats.

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shira mitchell @shiraamitchell.bsky.social · 29/04/2026

blog post: exploded logit ! a common choice model is multinomial logit. this model implies that rankings follow an exploded logit !

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shira mitchell @shiraamitchell.bsky.social · 23/04/2026

blog post: dCV for MRP Splitting a cluster between training and test fits models with more information than we should ("data leakage"). But not splitting a stratum between training and test fits models with LESS information than we should. bsky.app/profile/stat...

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shira mitchell @shiraamitchell.bsky.social · 15/04/2026

blog post: irrelevant alternatives ? a common choice model is multinomial logit. this model implies Independence of Irrelevant Alternatives (IIA), e.g. the ratio of Left-vs-Right preference is the same in round 1 as in the runoff.

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shira mitchell @shiraamitchell.bsky.social · 08/04/2026

blog post: improving with structure We’ve met Mr. P (Multilevel Regression and Poststratification). We’ve met Mrs. P (Multilevel Regression with Synthetic Poststratification). Now let’s meet Ms. P (Multilevel Structured regression with Poststratification).

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shira mitchell @shiraamitchell.bsky.social · 01/04/2026

blog post: design-based cross validation how to split train and test sets to respect survey design ? what lessons carry over to nonprobability samples ?

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shira mitchell @shiraamitchell.bsky.social · 25/03/2026

blog post: Individualism and the CV Noise Problem Politically meaningful differences among models can be swamped by cross-validation noise.

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shira mitchell @shiraamitchell.bsky.social · 18/03/2026

blog post: individualism doesn't work (even when weighted) individual-level loss (even weighted to the population) orders models differently than the population-level loss of interest to folks using MRP

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shira mitchell @shiraamitchell.bsky.social · 10/03/2026

blog post: work with us at Blue Rose ! use cutting edge statistics, machine learning, and engineering to study public opinion, forecast elections, and advise Democrats.

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shira mitchell @shiraamitchell.bsky.social · 03/03/2026

blog post: sampling-weighted loss we use sampling weights to estimate a population mean E(Y). what about to estimate a conditional mean E(Y|X) ? the best-fit model in the sample may not be the best-fit model in the population.

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shira mitchell @shiraamitchell.bsky.social · 25/02/2026

blog post: sampling to assess data quality @bhedtgauthier.bsky.social et al. (2012) used sampling to assess and improve data quality in Malawi

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shira mitchell @shiraamitchell.bsky.social · 17/02/2026

blog post: Gallup's Presidential Approval Ratings Gallup will no longer track presidential approval after 88 years Let's look at their sampling, mode, and weighting (still used for other survey questions)

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shira mitchell @shiraamitchell.bsky.social · 11/02/2026

blog post: more on recalled vote we've talked about measurement error in recalled vote in the US. how does this change in multiparty states ?

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Reposted by shira mitchell

David Shor @davidshor.bsky.social · 15/01/2026

We recently tested ~ a dozen public statements from a diverse set of Democratic elected officials on the murder of Renee Good and this was the top testing one

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