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Posts by Jan-Ole Fischer

Forward algorithm with homogeneous transition probability matrix β€” forward Calculates the log-likelihood of a sequence of observations under a homogeneous hidden Markov model using the forward algorithm.

Usage is simple: Existing RTMB machinery + passing a bandwidth argument to LaMa’s forward():

πŸ”— janolefi.github.io/LaMa/referen...

4 weeks ago 4 0 0 0

We develop a banded approximation to the forward algorithm (used to evaluate the HMM likelihood) thereby constructing the required sparsity.

The trade-off between computational efficiency and accuracy can be controlled by a single bandwidth parameter.

4 weeks ago 5 0 1 0

(R)TMB can integrate out high-dimensional random effects β€” such a those arising from the GMRF approximation of the SPDE approach β€” if the Hessian w.r.t. the random effects is sparse. This is not the case for the HMM likelihood because the observed process in HMMs is not Markovian.

4 weeks ago 3 0 1 0
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New preprint πŸ“‘ Fast inference in HMMs with latent Gaussian fields (via SPDE approach + RTMB) ⚑️

πŸ”— arxiv.org/abs/2603.17469

We modify the forward algorithm to recover a sparse Hessian ➑️ Fast automatic Laplace approximation

Case studies: 1) Detecting stellar flares 2) Lion movement w spatial field

4 weeks ago 13 3 1 0

LaMa and RTMBdist updated 😊

1 month ago 2 0 0 0
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Detecting disease progression from animal movement using hidden Markov models We demonstrate how (H)HMMs can be tailored to different epidemiological scenarios and provide a template workflow for developing and selecting Hidden Markov models to infer disease status from animal...

Published in @jappliedecology.bsky.social!πŸ˜€

We show how (Hierarchical) Hidden Markov Models ((H)HMMs) can be tailored to different epidemiological scenarios to infer disease status directly from animal movement data.

πŸ”— ttps://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2664.70323

1 month ago 27 19 1 1
Promotional image for webRios showing the app icon and an iPhone displaying the R console. The console shows example R commands with syntax highlighting: basic arithmetic (1 + 1), a print statement saying 'Hello from iOS!', a warning message in orange reading 'Uh-oh, I'm in the Apple-verse?', an error message in red with the HAL 9000 quote 'I'm sorry, Dave. I'm afraid I can't do that.', and a plot command.

Promotional image for webRios showing the app icon and an iPhone displaying the R console. The console shows example R commands with syntax highlighting: basic arithmetic (1 + 1), a print statement saying 'Hello from iOS!', a warning message in orange reading 'Uh-oh, I'm in the Apple-verse?', an error message in red with the HAL 9000 quote 'I'm sorry, Dave. I'm afraid I can't do that.', and a plot command.

webRios is live. #rstats on your iPhone and iPad.

I showed native R compilation on #iOS last week. Shipping it is another story (thanks, GPL). This version uses #webR 's #WebAssembly build instead. Different tradeoffs, but this one clears App Review.

apps.apple.com/us/app/webri...

2 months ago 82 29 5 4
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We have a new preprint on covariate-driven #HMMs!
doi.org/10.48550/arX...
@olemole.bsky.social, @rolandlangrock.bsky.social
β€’ commonly used hypothetical stationary distribution can be biased⚠️
β€’ we propose 2 approaches allowing unbiased inference
β€’ simulations and case study on GalΓ‘pagos tortoisesπŸ’πŸ—ΊοΈ

3 months ago 4 3 0 1
The 'bpvars' package for Forecasting with Bayesian Panel Vector Autoregressions

The 'bpvars' package for Forecasting with Bayesian Panel Vector Autoregressions

β¬›πŸŸ¦βšͺ Two years in the making! In a fantastic collaboration with Miguel from the International Labour Organisation! πŸ–€πŸ’™ The 'bpvars' package for Forecasting with Bayesian Panel Vector Autoregressions is out on CRAN! And it's spectacular!
cran.r-project.org/package=bpvars
#bpvars #bsvars.org #rstats

4 months ago 10 4 0 0

And that assessment is totally unbiased ofc πŸ˜‚

4 months ago 0 0 1 0
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Comparison between true state probabilities, stationary approximation, and periodically stationary distribution for three different simulated Markov Chains. The bias of the stationary distribution is severe.

Comparison between true state probabilities, stationary approximation, and periodically stationary distribution for three different simulated Markov Chains. The bias of the stationary distribution is severe.

Overall dwell-time distribution in the active state of the fruit flies in two light conditions. Both distributions deviate substantially from a geometric one.

Overall dwell-time distribution in the active state of the fruit flies in two light conditions. Both distributions deviate substantially from a geometric one.

Using #simulations and a case study on #fruitflies πŸͺ°, we show that
- the widely used stationary approximation can be severely biased! ❌
- dwell-time distributions can deviate substantially from a #geometric shape.

#HMM #MarkovChain #seasonality #diel #stats #rstats #StatisticalEcology #behaviour

4 months ago 3 0 1 0
Periodically stationary distribution (probability that the fly is active) as a function of the time of day.
True stationary distribution is compared to biased approximation, and we see a substantial difference.

Periodically stationary distribution (probability that the fly is active) as a function of the time of day. True stationary distribution is compared to biased approximation, and we see a substantial difference.

Our paper on #HMMs with periodically ⏰ varying transition probabilities is published! πŸŽ‰ @carlinafeldmann.bsky.social, Sina Mews, @rmichels.bsky.social @rolandlangrock.bsky.social

doi.org/10.1214/25-AOAS2107

We derive the periodically #stationary distribution and the implied dwell-time distribution

4 months ago 14 5 1 0
Screenshot of an item in the new R-devel release, that says:

x %notin% table newly in base is an idiom for !(x %in% table) and provided almost entirely for convenience and code readability, from an R-devel suggestion, after many years of private definitions mostly hidden in packages, including in R's tools package.

Screenshot of an item in the new R-devel release, that says: x %notin% table newly in base is an idiom for !(x %in% table) and provided almost entirely for convenience and code readability, from an R-devel suggestion, after many years of private definitions mostly hidden in packages, including in R's tools package.

%notin% is coming to Base R! Heck to the yes.

We are truly blessed on this day, thank you R Core. 🀩

#rstats

4 months ago 55 7 4 2
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Tools to Make Developing R Packages Easier Collection of package development tools.

Day 2: devtools - Essential Development Workflow πŸ”§

The devtools package streamlines your package development workflow with key functions! ⚑

πŸ’‘ Pro Tip: Use Ctrl/Cmd + Shift + L in RStudio to quickly run load_all().

πŸ“š Resources: devtools.r-lib.org

#RPackageDev #RStats #devtools #RPackageAdvent2025

4 months ago 10 3 1 0
Figure with two panels. Left panel: visualisation of a 3D movement track. Right panel: visualisation of the 3D direction of movement as two angles (one horizontal angle and one vertical angle).

Figure with two panels. Left panel: visualisation of a 3D movement track. Right panel: visualisation of the 3D direction of movement as two angles (one horizontal angle and one vertical angle).

We have a preprint about modelling three-dimensional movement tracks, led by @njklappstein.bsky.social.

The model takes the form of a step selection function and, just like in 2D, it can include directional persistence, attraction to targets, and habitat selection.

doi.org/10.1101/2025...

4 months ago 16 6 0 1
Version history of moveHMM R package, showing version 1.0 dated 2015-10-23

Version history of moveHMM R package, showing version 1.0 dated 2015-10-23

moveHMM version 1.0 turns 10 today πŸŽ‰ Such a fun 10 years; exchanging with folks who use the package (and its extensions) has been one of the best parts of my job!

5 months ago 17 2 1 0
Fast Numerical Maximum Likelihood Estimation for Latent Markov Models A variety of latent Markov models, including hidden Markov models, hidden semi-Markov models, state-space models and continuous-time variants can be formulated and estimated within the same framework ...

The LaMa package provides a versatile framework for inference with latent Markov models, designed to make building such models fun and efficient.

Check out the vignettes and start building models! πŸ› οΈ
πŸ‘‰ janoleko.github.io/LaMa/

7 months ago 4 0 0 0

Our review paper on latent Markov models is now published in Statistical Modelling! πŸŽ‰ @rolandlangrock.bsky.social @SinaMews.

We discuss choosing the right time and space formulation and provide the R package πŸ“¦ LaMa for fast ⚑and flexible estimation.

πŸ“„ Paper: journals.sagepub.com/eprint/UETXX...

7 months ago 12 1 1 0
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Fast Numerical Maximum Likelihood Estimation for Latent Markov Models A variety of latent Markov models, including hidden Markov models, hidden semi-Markov models, state-space models and continuous-time variants can be formulated and estimated within the same framework ...

All the relevant methodology is fully implemented πŸ› οΈ in my R package LaMa πŸ¦™:

janoleko.github.io/LaMa/

1 year ago 4 0 0 0
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Hidden semi-Markov models with inhomogeneous state dwell-time distributions The well-established methodology for the estimation of hidden semi-Markov models (HSMMs) as hidden Markov models (HMMs) with extended state spaces is …

My paper is out! πŸŽ‰ I explore hidden semi-Markov models with covariate-dependent state dwell-time distributions β€” because sometimes Markov just isn’t enough.
Case study: Arctic muskox movement! πŸ¦¬πŸ“Š
πŸ”— www.sciencedirect.com/science/arti...

#stats #TimeSeries #HSMM #StatisticalEcology #rstats

1 year ago 8 2 1 0
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Rdatasets is a collection of 2300 free and documented datasets in CSV format. It's a great resource for teaching and exploration!

The new `get_dataset()` function from the {marginaleffects} πŸ“¦ allows you to search and load them directly in #Rstats.

vincentarelbundock.github.io/Rdatasets/ar...

1 year ago 101 28 2 0
Popular meme format, grandma labeled with "bluesky's public launch was one year ago today." Younger person helping her labeled with "sure grandma let's get you to bed."

Popular meme format, grandma labeled with "bluesky's public launch was one year ago today." Younger person helping her labeled with "sure grandma let's get you to bed."

happy first birthday to Bluesky, and what a year it's been!

with every day, the need for an open network that puts people first becomes increasingly clear. we're glad to be building this with you. after all, the heart of a social network is the people.

1 year ago 153317 13833 3463 1656
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The world is on πŸ”₯ -- and here's my first publication in an astronomy journal: iopscience.iop.org/article/10.3...

We combine Gaussian processes + hidden Markov models to efficiently detect stellar flares in one modelling step. πŸ§ͺ

1 year ago 40 9 2 1
Video

Could watch this animation all day 😍

Did you know that you can create GIFs with gganimate()? They can even be embedded in a latex PDF file and played via Adobe Acorbat Reader πŸ’₯

#ggplot #gganimate #datavisualisation #statisticalmodelling #finance #economics #quants

1 year ago 7 2 1 0
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I'm just saying this is syntatically correct #rstats code

1 year ago 119 21 16 10
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2024 @copernicusecmwf.bsky.social #climate data out today:

πŸ“ˆ 2024 - first year more than 1.5Β°C above pre-industrial; for ERA5 it was 1.6ΒΊC
🌑️ the past 10 years were the 10 warmest years on record
πŸ“ˆ 2024 was warmest year for all continental regions, except Antarctica and Australasia

🌍🌑️πŸ§ͺβš’οΈπŸŒŠ

1 year ago 156 107 6 6
On Theoretical Foundations of Diffusion Models
On Theoretical Foundations of Diffusion Models YouTube video by C3 Digital Transformation Institute

Quite a nice watch:
youtu.be/TE4R8bumI-Q?...

1 year ago 36 4 0 0
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HMMotion: Using tracking data to predict coverage Explore and run machine learning code with Kaggle Notebooks | Using data from multiple data sources

Full kaggle notebook:

www.kaggle.com/code/rouvenm...

1 year ago 3 0 0 0
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In this yearβ€˜s NFL Big Data Bowl 🏈 submission, @rmichels.bsky.social, Robert Bajons, and I employ hidden Markov models to uncover πŸ”Žguarding assignments and use this additional information to improve the prediction of defensive strategies. πŸ“Š
#bigdatabowl #rstats

1 year ago 8 1 3 0

Big Data Bowl submissions are due tomorrow

🚨🚨

The deadline is 11:59 PM UTC, which is 6:59 PM EST

🚨🚨

#BigDataBowl

1 year ago 9 2 2 0