# \#bug

**URL:** https://discourse.pymc.io/tag/bug/9.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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## [Did state-space models change the way they handle time-varying matrices?](https://discourse.pymc.io/t/did-state-space-models-change-the-way-they-handle-time-varying-matrices/17950)

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**Author:** [@JSR](https://discourse.pymc.io/u/JSR)\
**Replies:** 3\
**Last updated:** [September 30, 2026, 9:41pm UTC](https://discourse.pymc.io/t/did-state-space-models-change-the-way-they-handle-time-varying-matrices/17950 "2026-09-30T21:41:22Z")

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I recently installed pymc on my windows computer using the pip installer. The following code works on my linux machine, which has an older version installed via conda. It doesn’t work on my windows laptop. import numpy …

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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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## [Bug in nutpie+numba: memory needed for LogNormal compilation scales superlinearly](https://discourse.pymc.io/t/bug-in-nutpie-numba-memory-needed-for-lognormal-compilation-scales-superlinearly/17911)

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**Author:** [@bridgeland](https://discourse.pymc.io/u/bridgeland)\
**Replies:** 4\
**Last updated:** [August 17, 2026, 3:34pm UTC](https://discourse.pymc.io/t/bug-in-nutpie-numba-memory-needed-for-lognormal-compilation-scales-superlinearly/17911 "2026-08-17T15:34:29Z")

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I discovered a bug in nutpie compilation. A model that conditions a LogNormal consumes far more memory in nutpie compilation than an otherwise identical model that conditions a Gamma. The ratio of memory usage between Lo…

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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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## [Issues with PyMC Marekting on Databricks](https://discourse.pymc.io/t/issues-with-pymc-marekting-on-databricks/17677)

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**Author:** [@Dominika](https://discourse.pymc.io/u/Dominika)\
**Replies:** 2\
**Last updated:** [April 23, 2026, 6:50am UTC](https://discourse.pymc.io/t/issues-with-pymc-marekting-on-databricks/17677 "2026-04-23T06:50:44Z")

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Hello, I’m runing an issue when installing pymc-marketing on a Databricks cluster. After installing the library (via Compute → Libraries), the Python REPL fails to start with the error: “Failure starting repl. Try det…

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## [Feedback requested: bioassay example, Windows RuntimeError, and docs improvements](https://discourse.pymc.io/t/feedback-requested-bioassay-example-windows-runtimeerror-and-docs-improvements/17596)

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**Author:** [@hridaii](https://discourse.pymc.io/u/hridaii)\
**Replies:** 0\
**Last updated:** [February 27, 2026, 3:30pm UTC](https://discourse.pymc.io/t/feedback-requested-bioassay-example-windows-runtimeerror-and-docs-improvements/17596 "2026-02-27T15:30:36Z")

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Hi @fonnesbeck I’ve been working through your Data Umbrella talk on PyMC and found it extremely helpful. Thank you for the great introduction to PyMC. While following the example Bioassay Problem model, I encountered a…

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## [Can't log mmm model with pymc\_marketing.mlflow.log\_mmm](https://discourse.pymc.io/t/cant-log-mmm-model-with-pymc-marketing-mlflow-log-mmm/17591)

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**Author:** [@fountainpen](https://discourse.pymc.io/u/fountainpen)\
**Replies:** 3\
**Last updated:** [February 27, 2026, 2:10am UTC](https://discourse.pymc.io/t/cant-log-mmm-model-with-pymc-marketing-mlflow-log-mmm/17591 "2026-02-27T02:10:49Z")

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pymc version: 5.27.1 pymc marketing version: 0.18.2 I am getting the following error on pymc\_marketing.mlflow.log\_mmm TypeError: log\_model() got an unexpected keyword argument 'name' # Log model configuration (satur…

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## [Multiprocessing problems on linux](https://discourse.pymc.io/t/multiprocessing-problems-on-linux/17569)

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**Author:** [@JSR](https://discourse.pymc.io/u/JSR)\
**Replies:** 7\
**Last updated:** [February 24, 2026, 2:55pm UTC](https://discourse.pymc.io/t/multiprocessing-problems-on-linux/17569 "2026-02-24T14:55:04Z")

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I’m on a fresh (as of last night) reinstall of Ubuntu 24.04.4 LTS, and pyMC (v 5.27.1) is giving me multiprocessing errors. I followed the recommended installation via Anaconda (conda 26.1.0), with python 3.14.3. It’s d…

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## [TimeSliceCrossValidator breaks when passing rng in sampler](https://discourse.pymc.io/t/timeslicecrossvalidator-breaks-when-passing-rng-in-sampler/17571)

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**Author:** [@fountainpen](https://discourse.pymc.io/u/fountainpen)\
**Replies:** 5\
**Last updated:** [February 19, 2026, 8:19pm UTC](https://discourse.pymc.io/t/timeslicecrossvalidator-breaks-when-passing-rng-in-sampler/17571 "2026-02-19T20:19:47Z")

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Pymc marketing version used: 0.18.0 In the cross validation 0.18.0 guide rng is set to rng: np.random.Generator = np.random.default\_rng(seed=seed). cv is then run with results = cv.run( X, y, # You can als…

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## [Possible bug: sample\_prior\_predictive with JAX fails for time-varying statespace models](https://discourse.pymc.io/t/possible-bug-sample-prior-predictive-with-jax-fails-for-time-varying-statespace-models/17549)

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**Author:** [@JSR](https://discourse.pymc.io/u/JSR)\
**Replies:** 2\
**Last updated:** [February 17, 2026, 8:37pm UTC](https://discourse.pymc.io/t/possible-bug-sample-prior-predictive-with-jax-fails-for-time-varying-statespace-models/17549 "2026-02-17T20:37:38Z")

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In the code below, sample\_prior\_predictive(compile\_kwargs={“mode”: “JAX”}) fails for the time-varying model. (Simple one-state model with exponential decay and a source term which may or may not change with time.) Also,…

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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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## [Sample\_smc stalls at final stage](https://discourse.pymc.io/t/sample-smc-stalls-at-final-stage/15055)

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**Author:** [@rubvber](https://discourse.pymc.io/u/rubvber)\
**Replies:** 20\
**Last updated:** [January 2, 2026, 7:53pm UTC](https://discourse.pymc.io/t/sample-smc-stalls-at-final-stage/15055 "2026-01-02T19:53:05Z")

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This is an issue I’ve experienced on multiple machines now (both on Windows and on Linux). I run sample\_smc (4 cores, 4 chains, 10,000 draws per chain) and it goes along merrily through the stages, until it reaches the f…

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## [New Contributor to PyMC Community](https://discourse.pymc.io/t/new-contributor-to-pymc-community/17504)

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**Author:** [@Subhra\_Jyoti\_Das](https://discourse.pymc.io/u/Subhra_Jyoti_Das)\
**Replies:** 0\
**Last updated:** [December 31, 2025, 8:00pm UTC](https://discourse.pymc.io/t/new-contributor-to-pymc-community/17504 "2025-12-31T20:00:04Z")

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Hello everyone! My name is Subhra Jyoti Das, a second-year engineering student at the Indian Institute of Technology Roorkee (IIT Roorkee). I have a strong interest in artificial intelligence, machine learning, and deep…

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## [SMC Sampling Issues in PyMC v5 - Extremely Slow Progress and NotImplementedError](https://discourse.pymc.io/t/smc-sampling-issues-in-pymc-v5-extremely-slow-progress-and-notimplementederror/17418)

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**Author:** [@majf](https://discourse.pymc.io/u/majf)\
**Replies:** 9\
**Last updated:** [November 10, 2025, 9:01am UTC](https://discourse.pymc.io/t/smc-sampling-issues-in-pymc-v5-extremely-slow-progress-and-notimplementederror/17418 "2025-11-10T09:01:23Z")

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Hi PyMC Community, I’m trying to use SMC sampling in PyMC v5 to compute marginal likelihoods for Bayesian model comparison, but I’m running into persistent issues. I have four different models, and in all cases, SMC sam…

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## [OverflowError: Python int too large to convert to C long](https://discourse.pymc.io/t/overflowerror-python-int-too-large-to-convert-to-c-long/17392)

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**Author:** [@ccyang](https://discourse.pymc.io/u/ccyang)\
**Replies:** 14\
**Last updated:** [October 21, 2025, 11:47am UTC](https://discourse.pymc.io/t/overflowerror-python-int-too-large-to-convert-to-c-long/17392 "2025-10-21T11:47:50Z")

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I’m stuck on an error. I’m looking for a solution, and I also hope to use this case to learn how to debug PyMC models. The following is a small BART model that reproduces an OverflowError. I encountered the same issue w…

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## [Nutpie sampling freezes](https://discourse.pymc.io/t/nutpie-sampling-freezes/17372)

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**Author:** [@bridgeland](https://discourse.pymc.io/u/bridgeland)\
**Replies:** 12\
**Last updated:** [October 16, 2025, 9:16pm UTC](https://discourse.pymc.io/t/nutpie-sampling-freezes/17372 "2025-10-16T21:16:48Z")

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I tried nutpie for the first time on my rather large model. nutpie compiled the model without reporting any difficulty. But sampling resulted in a curious failure: it starts sampling, but freezes after two minutes. No ne…

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## [How to debug a model when most chains sample fine, but a few do not?](https://discourse.pymc.io/t/how-to-debug-a-model-when-most-chains-sample-fine-but-a-few-do-not/17383)

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**Author:** [@bridgeland](https://discourse.pymc.io/u/bridgeland)\
**Replies:** 1\
**Last updated:** [October 15, 2025, 1:30pm UTC](https://discourse.pymc.io/t/how-to-debug-a-model-when-most-chains-sample-fine-but-a-few-do-not/17383 "2025-10-15T13:30:25Z")

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I have a rather complex model that samples well most of the time. But sometimes one of the chains samples very differently from the others. For example, here is the plot\_trace for one of the RVs in one of the sampling ru…

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## [Pymc marketing sample\_posterior\_predictive (Bug)](https://discourse.pymc.io/t/pymc-marketing-sample-posterior-predictive-bug/17371)

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**Author:** [@fountainpen](https://discourse.pymc.io/u/fountainpen)\
**Replies:** 0\
**Last updated:** [October 8, 2025, 5:53pm UTC](https://discourse.pymc.io/t/pymc-marketing-sample-posterior-predictive-bug/17371 "2025-10-08T17:53:50Z")

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Version: 0.16.0 When using mmm.sample\_posterior\_predictive setting original\_scale=True will only affect ‘y’ variable like so if original\_scale: if hasattr(self, "target\_scale"): # Use the new computed scale…

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## [Model too complex to compile?](https://discourse.pymc.io/t/model-too-complex-to-compile/17196)

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**Author:** [@mike-lawrence](https://discourse.pymc.io/u/mike-lawrence)\
**Replies:** 2\
**Last updated:** [July 20, 2025, 6:52pm UTC](https://discourse.pymc.io/t/model-too-complex-to-compile/17196 "2025-07-20T18:52:18Z")

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Hey folks, I’ve been banging my head on this for a while, and it also seems to have chatGPT thoroughly stumped, so I thought I’d impose upon the human experts here for some assistance. Error messages encountered: Below…

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## [Incorrect number of draws in SMC example](https://discourse.pymc.io/t/incorrect-number-of-draws-in-smc-example/17119)

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**Author:** [@rohingilman](https://discourse.pymc.io/u/rohingilman)\
**Replies:** 2\
**Last updated:** [June 19, 2025, 9:07am UTC](https://discourse.pymc.io/t/incorrect-number-of-draws-in-smc-example/17119 "2025-06-19T09:07:18Z")

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I am running the PyMC example code for SMC and there seems to be an issue with the number of draws for sample\_smc. I ran the code from the example (both in a notebook and as a script) with 5 chains. import arviz as az i…

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## [Nutpie panel data events "moving"](https://discourse.pymc.io/t/nutpie-panel-data-events-moving/17046)

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**Author:** [@KL\_Bean](https://discourse.pymc.io/u/KL_Bean)\
**Replies:** 7\
**Last updated:** [May 29, 2025, 2:43pm UTC](https://discourse.pymc.io/t/nutpie-panel-data-events-moving/17046 "2025-05-29T14:43:19Z")

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pymc version: 5.21.1 nutpie version 0.14.3 When I try to incorporate event data into a model with multiple locations, and allow the coefficient to vary by location, I am noticing that the “date” of the event is shiftin…

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## [Wierd problem installing PYMC](https://discourse.pymc.io/t/wierd-problem-installing-pymc/16984)

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**Author:** [@DrEntropy](https://discourse.pymc.io/u/DrEntropy)\
**Replies:** 17\
**Last updated:** [May 13, 2025, 7:24pm UTC](https://discourse.pymc.io/t/wierd-problem-installing-pymc/16984 "2025-05-13T19:24:51Z")

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I was just starting a new project, like I normally do, and tried installing pymc like this: conda create -n multinom3 python=3.12 pymc=5.21.0 arviz jupyter -c conda-forge This is on windows 11. Note I pinned these ve…

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## [Why the (automatic) nested CompoundStep Fails?](https://discourse.pymc.io/t/why-the-automatic-nested-compoundstep-fails/16675)

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**Author:** [@fruzti](https://discourse.pymc.io/u/fruzti)\
**Replies:** 2\
**Last updated:** [March 11, 2025, 9:29am UTC](https://discourse.pymc.io/t/why-the-automatic-nested-compoundstep-fails/16675 "2025-03-11T09:29:14Z")

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Hi all, I’m trying to implement a simple model based on two-classes Gaussian clustering with particular priors on the ratios of the clases. However, it seems that I’m running on an issue when pymc automatically group va…

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## [AttributeError: 'numpy.ndarray' object has no attribute 'at' when sampling LKJ Cholesky Covariance Priors for Multivariate Normal Models example with numpyro or blackjax](https://discourse.pymc.io/t/attributeerror-numpy-ndarray-object-has-no-attribute-at-when-sampling-lkj-cholesky-covariance-priors-for-multivariate-normal-models-example-with-numpyro-or-blackjax/16598)

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**Author:** [@EhDings](https://discourse.pymc.io/u/EhDings)\
**Replies:** 4\
**Last updated:** [February 26, 2025, 1:53pm UTC](https://discourse.pymc.io/t/attributeerror-numpy-ndarray-object-has-no-attribute-at-when-sampling-lkj-cholesky-covariance-priors-for-multivariate-normal-models-example-with-numpyro-or-blackjax/16598 "2025-02-26T13:53:43Z")

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I wanted to try out sampling with numpyro on an AMD GPU using a model based on this example: https://www.pymc.io/projects/examples/en/latest/howto/LKJ.html It works with PyMC and nutpie samplers, but not with jax sampl…

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## [State Space: Exogenous Vars - Conflicting dimensions for time](https://discourse.pymc.io/t/state-space-exogenous-vars-conflicting-dimensions-for-time/16521)

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**Author:** [@rOy\_bOy](https://discourse.pymc.io/u/rOy_bOy)\
**Replies:** 26\
**Last updated:** [February 24, 2025, 9:53pm UTC](https://discourse.pymc.io/t/state-space-exogenous-vars-conflicting-dimensions-for-time/16521 "2025-02-24T21:53:59Z")

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Hey PyMC & @jessegrabowski , I’m trying to use state space’s forecast method with exogenous variables, but I keep getting this error: ValueError: conflicting sizes for dimension ‘time’: length 1107 on the data but len…

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## [Error with custom distribution after using scan](https://discourse.pymc.io/t/error-with-custom-distribution-after-using-scan/16255)

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**Author:** [@Juan\_Martinez](https://discourse.pymc.io/u/Juan_Martinez)\
**Replies:** 11\
**Last updated:** [February 24, 2025, 5:25pm UTC](https://discourse.pymc.io/t/error-with-custom-distribution-after-using-scan/16255 "2025-02-24T17:25:24Z")

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Hi all, While building a time series model I’m encountering the following error: ValueError: traffic\_innov is not in list. When I look at the list in question, I do find a variable named traffic\_innov, so my best hypoth…

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## [Blackjax sampler suffers divergences with TruncatedNormal likelihood](https://discourse.pymc.io/t/blackjax-sampler-suffers-divergences-with-truncatednormal-likelihood/16469)

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**Author:** [@noahg](https://discourse.pymc.io/u/noahg)\
**Replies:** 5\
**Last updated:** [February 3, 2025, 2:25pm UTC](https://discourse.pymc.io/t/blackjax-sampler-suffers-divergences-with-truncatednormal-likelihood/16469 "2025-02-03T14:25:53Z")

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Hi there! I’ve recently been trying out the jax-based samplers (blackjax in particular), but I’ve noticed some unexpected behavior when working with a model that has a TruncatedNormal likelihood. PyMC’s default NUTS samp…

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## [Scan related error using nutpie for an autoregressive model](https://discourse.pymc.io/t/scan-related-error-using-nutpie-for-an-autoregressive-model/16395)

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**Author:** [@Juan\_Martinez](https://discourse.pymc.io/u/Juan_Martinez)\
**Replies:** 4\
**Last updated:** [January 29, 2025, 10:53am UTC](https://discourse.pymc.io/t/scan-related-error-using-nutpie-for-an-autoregressive-model/16395 "2025-01-29T10:53:28Z")

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Hi all, I’m getting the following error when trying to use nutpie (“standard” sampling works) for an autoregressive model. Any contribution is appreciated. ValueError: Argument Sigmoid.0 given to the scan node is not c…

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## [Dataset size dependent EOFError](https://discourse.pymc.io/t/dataset-size-dependent-eoferror/11977)

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**Author:** [@davipatti](https://discourse.pymc.io/u/davipatti)\
**Replies:** 14\
**Last updated:** [January 26, 2025, 11:13am UTC](https://discourse.pymc.io/t/dataset-size-dependent-eoferror/11977 "2025-01-26T11:13:14Z")

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Hello I’m running the following model: import numpy as np import pymc as pm import pytensor.tensor as tt # simulate some data np.random.seed(42) n = 10\_000 # number of individuals group\_size = n // 2 t = 12 # numb…

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## [PyMC gradually slows down](https://discourse.pymc.io/t/pymc-gradually-slows-down/16279)

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**Author:** [@Gabriella\_Chaos](https://discourse.pymc.io/u/Gabriella_Chaos)\
**Replies:** 14\
**Last updated:** [December 23, 2024, 2:52am UTC](https://discourse.pymc.io/t/pymc-gradually-slows-down/16279 "2024-12-23T02:52:35Z")

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I am running a series of Bayesian updating. For each step, a new model context is created, and statistics are collected after sampling for further update. I observed that the sampling time are gradually increasing as the…

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