# \#modeling

**URL:** https://discourse.pymc.io/tag/modeling/39.md

[Latest](https://discourse.pymc.io/latest.md) · [Categories](https://discourse.pymc.io/categories.md) · [Tags](https://discourse.pymc.io/tags.md)

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## [Contributions to State-Space Models & Project Ideas for PyMC-Extras](https://discourse.pymc.io/t/contributions-to-state-space-models-project-ideas-for-pymc-extras/17935)

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**Author:** [@Dhairya](https://discourse.pymc.io/u/Dhairya)\
**Replies:** 2\
**Last updated:** [September 14, 2026, 7:33am UTC](https://discourse.pymc.io/t/contributions-to-state-space-models-project-ideas-for-pymc-extras/17935 "2026-09-14T07:33:40Z")

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Hi all, I have contributed a few fixes within the PyMC projects: \[pymc#8322\] (merged): Propagating dimensions in \`LatentKron\` Gaussian Processes. \[pymc-extras#763\]: Mode using point estimates for post-estimation in \`s…

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## [DEMetropolis stalls with progressbar=True](https://discourse.pymc.io/t/demetropolis-stalls-with-progressbar-true/17925)

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**Author:** [@excaliburrrrrrrrr](https://discourse.pymc.io/u/excaliburrrrrrrrr)\
**Replies:** 6\
**Last updated:** [September 9, 2026, 9:07am UTC](https://discourse.pymc.io/t/demetropolis-stalls-with-progressbar-true/17925 "2026-09-09T09:07:49Z")

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Hi everyone, I rely on MCMC progress and estimated remaining time to schedule subsequent computations. With parallel DEMetropolis, enabling the progress bar appears to stall my job. Disabling it allows completion, but l…

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## [Setting and justifying priors for a discrete "what went wrong" model when I have no labeled data](https://discourse.pymc.io/t/setting-and-justifying-priors-for-a-discrete-what-went-wrong-model-when-i-have-no-labeled-data/17917)

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**Author:** [@ChiragG2101](https://discourse.pymc.io/u/ChiragG2101)\
**Replies:** 1\
**Last updated:** [September 3, 2026, 4:31pm UTC](https://discourse.pymc.io/t/setting-and-justifying-priors-for-a-discrete-what-went-wrong-model-when-i-have-no-labeled-data/17917 "2026-09-03T16:31:38Z")

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I’m modeling a data-quality decision as a small discrete belief problem and would love a sanity check from people who do this properly (I’m a software engineer, newer to Bayesian methods). For each scraped product-spe…

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## [Small-N Bayesian Poisson regression, sign flip on leave-one-out — sanity check on approach?](https://discourse.pymc.io/t/small-n-bayesian-poisson-regression-sign-flip-on-leave-one-out-sanity-check-on-approach/17921)

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**Author:** [@Alex25](https://discourse.pymc.io/u/Alex25)\
**Replies:** 2\
**Last updated:** [August 30, 2026, 3:10pm UTC](https://discourse.pymc.io/t/small-n-bayesian-poisson-regression-sign-flip-on-leave-one-out-sanity-check-on-approach/17921 "2026-08-30T15:10:03Z")

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Working on a small applied project: testing whether a technical “readiness” score for e-commerce vendors predicts how often an LLM agent mentions them in purchase-recommendation queries. Poisson regression, mentions ~ No…

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## [Priors, begginer questions and Titanic Data](https://discourse.pymc.io/t/priors-begginer-questions-and-titanic-data/17892)

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**Author:** [@Pegguins](https://discourse.pymc.io/u/Pegguins)\
**Replies:** 1\
**Last updated:** [July 31, 2026, 6:00pm UTC](https://discourse.pymc.io/t/priors-begginer-questions-and-titanic-data/17892 "2026-07-31T18:00:47Z")

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Hello, Apologies for the likely common and oft repeated prior quandary. I’ve been reading through the excellent examples, questions here, and articles such as this one by the Stan team: Prior Choice Recommendations · st…

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## [Hierarchical model with copula on GPU: NumPyro or nutpie using PyMC 5.19?](https://discourse.pymc.io/t/hierarchical-model-with-copula-on-gpu-numpyro-or-nutpie-using-pymc-5-19/17853)

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**Author:** [@user-jiyichen](https://discourse.pymc.io/u/user-jiyichen)\
**Replies:** 3\
**Last updated:** [July 9, 2026, 2:25pm UTC](https://discourse.pymc.io/t/hierarchical-model-with-copula-on-gpu-numpyro-or-nutpie-using-pymc-5-19/17853 "2026-07-09T14:25:45Z")

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My compute cluster only supports PyMC 5.19 using Python 3.12.4, and I need to fit a bivariate joint model with copulas and two quite complicated marginal models (~2k parameters). It took ~5 hours for 5k warmups + 5k ite…

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## [Help to speed up sampling -- too long to be clinically practical](https://discourse.pymc.io/t/help-to-speed-up-sampling-too-long-to-be-clinically-practical/17852)

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**Author:** [@hd2005](https://discourse.pymc.io/u/hd2005)\
**Replies:** 16\
**Last updated:** [June 25, 2026, 5:42am UTC](https://discourse.pymc.io/t/help-to-speed-up-sampling-too-long-to-be-clinically-practical/17852 "2026-06-25T05:42:52Z")

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Hi all, I am using pymc to perform a 3-parameter mono-exponential decay fitting (y = A exp(-t/T2)+B); However, it takes 4 seconds to complete one fitting task. For comparison, it only takes scipy.curve\_fit 1.5ms to comp…

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## [Hiring: Founding Bayesian / ML Engineer — MMM platform (remote EU, equity + cash)](https://discourse.pymc.io/t/hiring-founding-bayesian-ml-engineer-mmm-platform-remote-eu-equity-cash/17700)

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**Author:** [@CalybraFounder](https://discourse.pymc.io/u/CalybraFounder)\
**Replies:** 1\
**Last updated:** [June 16, 2026, 1:49pm UTC](https://discourse.pymc.io/t/hiring-founding-bayesian-ml-engineer-mmm-platform-remote-eu-equity-cash/17700 "2026-06-16T13:49:44Z")

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Pre-seed startup in Europe building a hierarchical Bayesian Marketing Mix Modeling platform. Looking for a founding engineer who has shipped serious probabilistic programming to production, ideally with hierarchical mode…

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## [Gradientless sampler on the GPU through PyMc?](https://discourse.pymc.io/t/gradientless-sampler-on-the-gpu-through-pymc/17847)

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**Author:** [@Bandit](https://discourse.pymc.io/u/Bandit)\
**Replies:** 1\
**Last updated:** [June 16, 2026, 2:13am UTC](https://discourse.pymc.io/t/gradientless-sampler-on-the-gpu-through-pymc/17847 "2026-06-16T02:13:46Z")

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Is there any way to use a gradientless sampler (e.g. Slice, ESS, or Randomwalk) on the GPU through PyMC? As best as I can tell, the least-friction option is to build the model using PyMC, extract it, and then run numpyro…

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## [Comparing evidence (Bayes Factors) for two competing posterior models as a (kind of) hypothesis test](https://discourse.pymc.io/t/comparing-evidence-bayes-factors-for-two-competing-posterior-models-as-a-kind-of-hypothesis-test/17819)

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**Author:** [@cmcnorgan](https://discourse.pymc.io/u/cmcnorgan)\
**Replies:** 3\
**Last updated:** [June 15, 2026, 7:22pm UTC](https://discourse.pymc.io/t/comparing-evidence-bayes-factors-for-two-competing-posterior-models-as-a-kind-of-hypothesis-test/17819 "2026-06-15T19:22:52Z")

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I’m looking at mean differences between salary two groups (Male vs. Female) in a synthetic dataset. Gender was determined randomly, so the ground truth is that there is no gender difference. At the end of the day, I’m l…

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## [Bayesian Experimentation and Clinical Trial Design (Help wanted)](https://discourse.pymc.io/t/bayesian-experimentation-and-clinical-trial-design-help-wanted/17815)

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**Author:** [@Nathaniel\_Forde](https://discourse.pymc.io/u/Nathaniel_Forde)\
**Replies:** 0\
**Last updated:** [June 3, 2026, 12:16pm UTC](https://discourse.pymc.io/t/bayesian-experimentation-and-clinical-trial-design-help-wanted/17815 "2026-06-03T12:16:53Z")

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In light of the FDA guidance on Bayesian experimentation i thought it might be worth adding documentation to pymc examples on themes of: bayesian assurance, sensitivity analysis and meta analysis See PR here: Add Bayesi…

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## [Laplace approximation vs VI](https://discourse.pymc.io/t/laplace-approximation-vs-vi/17722)

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**Author:** [@jaj](https://discourse.pymc.io/u/jaj)\
**Replies:** 10\
**Last updated:** [June 2, 2026, 4:20pm UTC](https://discourse.pymc.io/t/laplace-approximation-vs-vi/17722 "2026-06-02T16:20:15Z")

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Hi, I’m looking at how VI and Laplace approximation work and they seem very similar to me. The fit\_laplace function in pymc-extras approximates the parameter space with a multivariate normal, matches the normal means t…

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## [Implementing late-entering series in a PyMC state-space model](https://discourse.pymc.io/t/implementing-late-entering-series-in-a-pymc-state-space-model/17714)

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**Author:** [@pritam](https://discourse.pymc.io/u/pritam)\
**Replies:** 6\
**Last updated:** [June 1, 2026, 6:09pm UTC](https://discourse.pymc.io/t/implementing-late-entering-series-in-a-pymc-state-space-model/17714 "2026-06-01T18:09:11Z")

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Hi all, I am trying to implement a multivariate state-space model in PyMC for compositional time-series data. Suppose I have multiple related time series observed over a common time index, but some series only begin pa…

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## [Is BART currently broken for out of sample predictions?](https://discourse.pymc.io/t/is-bart-currently-broken-for-out-of-sample-predictions/17720)

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**Author:** [@brontidon](https://discourse.pymc.io/u/brontidon)\
**Replies:** 3\
**Last updated:** [May 27, 2026, 10:23pm UTC](https://discourse.pymc.io/t/is-bart-currently-broken-for-out-of-sample-predictions/17720 "2026-05-27T22:23:46Z")

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Hey there, I recently updated to v6, and for a BART model I’ve noticed some interesting shape errors that until now have not been present. My script breaks when I attempt to create posterior predictive samples for my h…

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## [Parallelization of Sequential Monte Carlo: sample\_smc](https://discourse.pymc.io/t/parallelization-of-sequential-monte-carlo-sample-smc/17712)

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**Author:** [@janwi](https://discourse.pymc.io/u/janwi)\
**Replies:** 1\
**Last updated:** [May 15, 2026, 6:41am UTC](https://discourse.pymc.io/t/parallelization-of-sequential-monte-carlo-sample-smc/17712 "2026-05-15T06:41:30Z")

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Hello everyone, I am new to PyMC and I am planning to use the SMC sampler, pm.sample\_smc, for Bayesian parameter calibration. For example: pm.sample\_smc(draws=1000, chains=1, cores=1) One attractive feature of SMC me…

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## [Any Thoughts on Sequential Bayesian Update](https://discourse.pymc.io/t/any-thoughts-on-sequential-bayesian-update/17711)

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**Author:** [@Gumibear\_Toronto](https://discourse.pymc.io/u/Gumibear_Toronto)\
**Replies:** 2\
**Last updated:** [May 14, 2026, 1:18pm UTC](https://discourse.pymc.io/t/any-thoughts-on-sequential-bayesian-update/17711 "2026-05-14T13:18:28Z")

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Hi, I am working on using PyMC for (i) uncertainty quantification and (ii) sequential learning—a new data comes up sequentially. For better uncertainty quantification, using all the previous data as a batch to train my…

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## [Out of sample predictions with missing data](https://discourse.pymc.io/t/out-of-sample-predictions-with-missing-data/17698)

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**Author:** [@tnd](https://discourse.pymc.io/u/tnd)\
**Replies:** 2\
**Last updated:** [April 28, 2026, 3:32pm UTC](https://discourse.pymc.io/t/out-of-sample-predictions-with-missing-data/17698 "2026-04-28T15:32:41Z")

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Dear friends, I am looking for a way to do missing value imputation for out of sample data predictions. I am checking the tutorial GLM-missing-values-in-covariates, and I have a question about Section 2.5. When we do p…

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## [Timeseries binary-decision problem](https://discourse.pymc.io/t/timeseries-binary-decision-problem/17441)

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**Author:** [@Tester](https://discourse.pymc.io/u/Tester)\
**Replies:** 9\
**Last updated:** [April 9, 2026, 7:19pm UTC](https://discourse.pymc.io/t/timeseries-binary-decision-problem/17441 "2026-04-09T19:19:30Z")

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I have data from an experiment in which subjects repeatedly completed a specific task that required a forced binary decision (option A vs. B). I only observe this decision at the end of each recording. As predictors/IVs,…

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## [Question on Nested Logit for Retail Expansion](https://discourse.pymc.io/t/question-on-nested-logit-for-retail-expansion/17626)

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**Author:** [@skalilopa](https://discourse.pymc.io/u/skalilopa)\
**Replies:** 2\
**Last updated:** [April 8, 2026, 9:38am UTC](https://discourse.pymc.io/t/question-on-nested-logit-for-retail-expansion/17626 "2026-04-08T09:38:15Z")

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Hello, I am working on a store expansion strategy: identifying optimal locations for new store openings. My approach: • I divide the trade areAa into grid cells, each representing a population segment acting as a “con…

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## [Model's internal noise](https://discourse.pymc.io/t/models-internal-noise/17667)

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**Author:** [@ADv0rnik](https://discourse.pymc.io/u/ADv0rnik)\
**Replies:** 1\
**Last updated:** [March 30, 2026, 6:43pm UTC](https://discourse.pymc.io/t/models-internal-noise/17667 "2026-03-30T18:43:11Z")

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Hi community I’m trying to find a way to measure the pure noise produced by the model itself, assuming we have ideal observations (i.e., noise-free data). The key idea is to understand the model’s contribution to the ov…

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## [Fractional CTO — AI-powered football transfer intelligence platform (Bayesian/PyMC, Scotland)](https://discourse.pymc.io/t/fractional-cto-ai-powered-football-transfer-intelligence-platform-bayesian-pymc-scotland/17674)

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**Author:** [@Fraser](https://discourse.pymc.io/u/Fraser)\
**Replies:** 0\
**Last updated:** [March 29, 2026, 11:34pm UTC](https://discourse.pymc.io/t/fractional-cto-ai-powered-football-transfer-intelligence-platform-bayesian-pymc-scotland/17674 "2026-03-29T23:34:34Z")

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FitSim (fitsim.ai) is a pre-seed AI-powered football transfer intelligence platform based in Scotland. We use Bayesian inference and multi-system simulation to predict player performance, assess transfer risk, and quanti…

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## [GSoC 2026 Actuarial Survival Models: Tackling Left-Truncation & Declarative API Vision](https://discourse.pymc.io/t/gsoc-2026-actuarial-survival-models-tackling-left-truncation-declarative-api-vision/17669)

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**Author:** [@ZHANGSHUO22](https://discourse.pymc.io/u/ZHANGSHUO22)\
**Replies:** 0\
**Last updated:** [March 26, 2026, 8:50pm UTC](https://discourse.pymc.io/t/gsoc-2026-actuarial-survival-models-tackling-left-truncation-declarative-api-vision/17669 "2026-03-26T20:50:38Z")

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Hi PyMC Team and Mentors, My name is Shuo Zhang, an MSc grad in Financial & Insurance Mathematics at Charles University and an Actuary Candidate (passed SOA exams P & FM). I am incredibly excited about the Survival Mode…

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## [Inconsistent ROAS when migrating to multi-dim MMM class](https://discourse.pymc.io/t/inconsistent-roas-when-migrating-to-multi-dim-mmm-class/17488)

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**Author:** [@NRJ](https://discourse.pymc.io/u/NRJ)\
**Replies:** 5\
**Last updated:** [March 18, 2026, 10:52am UTC](https://discourse.pymc.io/t/inconsistent-roas-when-migrating-to-multi-dim-mmm-class/17488 "2026-03-18T10:52:12Z")

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Hello, I trained an MMM using pymc-marketing and realized that it’s probably better to migrate to the multi-dim MMM class for budget allocation analysis, even though I have a single geo to model. Despite keeping everyth…

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## [Can pm.Wishart be used as a likelihood for an observed sample covariance?](https://discourse.pymc.io/t/can-pm-wishart-be-used-as-a-likelihood-for-an-observed-sample-covariance/17629)

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**Author:** [@excaliburrrrrrrrr](https://discourse.pymc.io/u/excaliburrrrrrrrr)\
**Replies:** 6\
**Last updated:** [March 15, 2026, 1:55pm UTC](https://discourse.pymc.io/t/can-pm-wishart-be-used-as-a-likelihood-for-an-observed-sample-covariance/17629 "2026-03-15T13:55:02Z")

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Hi PyMC community, I’m building an inverse model to estimate parameters that control transport of multiple elements in a fluid system. My observations are summary statistics: (1) mean values and (2) covariance matrices …

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## [ONNX Probabilistic Programming Working Group – PyMC Community Involvement](https://discourse.pymc.io/t/onnx-probabilistic-programming-working-group-pymc-community-involvement/17612)

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**Author:** [@Brian\_Parbhu](https://discourse.pymc.io/u/Brian_Parbhu)\
**Replies:** 0\
**Last updated:** [March 7, 2026, 8:04pm UTC](https://discourse.pymc.io/t/onnx-probabilistic-programming-working-group-pymc-community-involvement/17612 "2026-03-07T20:04:52Z")

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Hi everyone, A new ONNX Working Group focused on probabilistic programming has recently been formed, and we’d love to involve members of the PyMC community. The goal of this effort is to bring probabilistic modeling an…

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## [Feb 5th Bayesian Data Analysis Meetup Virtual Event](https://discourse.pymc.io/t/feb-5th-bayesian-data-analysis-meetup-virtual-event/17534)

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**Author:** [@Brian\_Parbhu](https://discourse.pymc.io/u/Brian_Parbhu)\
**Replies:** 3\
**Last updated:** [February 23, 2026, 2:10am UTC](https://discourse.pymc.io/t/feb-5th-bayesian-data-analysis-meetup-virtual-event/17534 "2026-02-23T02:10:29Z")

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Hi All, On Feb 5 we have a virtual event for the Bayesian Data Analysis Meetup. We’re excited to host Ian Costley (Wegmans Food Markets) for an upcoming talk on Bayesian Models in Production. Ian will share hands-on ex…

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## [Could not broadcast error - works with pm.draw and the graph vis shows no problems](https://discourse.pymc.io/t/could-not-broadcast-error-works-with-pm-draw-and-the-graph-vis-shows-no-problems/17554)

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**Author:** [@thejasvibr](https://discourse.pymc.io/u/thejasvibr)\
**Replies:** 2\
**Last updated:** [February 12, 2026, 11:21pm UTC](https://discourse.pymc.io/t/could-not-broadcast-error-works-with-pm-draw-and-the-graph-vis-shows-no-problems/17554 "2026-02-12T23:21:25Z")

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Hi All, I’m trying to estimate mic position (Nmics,3 shape) and source location (Nsources,3 shape) given a set of time-differences of a sound’s arrival through approximate Bayesian Computing. I’m constantly getting Va…

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## [Potential Bug: Budget Optimizer Fails with Adstock Models (Dimension Mismatch)](https://discourse.pymc.io/t/potential-bug-budget-optimizer-fails-with-adstock-models-dimension-mismatch/17535)

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**Author:** [@paulf](https://discourse.pymc.io/u/paulf)\
**Replies:** 1\
**Last updated:** [February 3, 2026, 2:38pm UTC](https://discourse.pymc.io/t/potential-bug-budget-optimizer-fails-with-adstock-models-dimension-mismatch/17535 "2026-02-03T14:38:42Z")

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The ‘MultiDimensionalBudgetOptimizerWrapper.optimize\_budget()’ fails for me with a dimension mismatch error. The traceback returns a ValueError: Input dimension mismatch: (input\[2\].shape\[3\] = 53, input\[3\].shape\[3\] = 61),…

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## [Call for Contributors: Probabilistic Modeling & Bayesian Inference in ONNX](https://discourse.pymc.io/t/call-for-contributors-probabilistic-modeling-bayesian-inference-in-onnx/17545)

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**Author:** [@Brian\_Parbhu](https://discourse.pymc.io/u/Brian_Parbhu)\
**Replies:** 0\
**Last updated:** [January 31, 2026, 10:33pm UTC](https://discourse.pymc.io/t/call-for-contributors-probabilistic-modeling-bayesian-inference-in-onnx/17545 "2026-01-31T22:33:45Z")

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Hi everyone, I wanted to share an initiative that’s getting underway and invite feedback and participation from the PyMC community. We’re working with the ONNX ecosystem on a proposal to support probabilistic modeling …

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## [Model with a loop - scan conversion](https://discourse.pymc.io/t/model-with-a-loop-scan-conversion/17538)

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**Author:** [@SilentFormality](https://discourse.pymc.io/u/SilentFormality)\
**Replies:** 3\
**Last updated:** [January 29, 2026, 3:56pm UTC](https://discourse.pymc.io/t/model-with-a-loop-scan-conversion/17538 "2026-01-29T15:56:35Z")

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First time actually posting on a coding forum, so please let me know if anything needs clarified or edited. I have never used PYMC before, and I am attempting to calibrate a model, however, the model contains a for loop…

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