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Chronos: Learning the Language of Time Series

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Re: Chronos: Learning the Language of Time Series

#22
post #2

Doesn't cite TimesFM for some reason. Maybe the latter was published after this paper went camera-ready? https://blog.research.google/2024/02/a-decoder-only-foundati...

Because these approaches as likely derived from papers published 3-5 years ago. At this point neither TimesFM or Chronos is particularly novel. I've had similar models in production for complex time series for 18 months now.

Re: Chronos: Learning the Language of Time Series

#23

Maybe I'm missing something obvious, but what is the idea behind quantizing and tokenizing time series? We tokenize text because text isn't numbers. In the case of time series, we're... turning numbers into less precise numbers? The benefit of scaling and centering is trivial and i guess all timeseries ML does it, but I don't see why we need a token after that.

I'm building upon insights from this paper (https://arxiv.org/pdf/2403.03950.pdf) and believe that classification can sometimes outperform regression, even when dealing with continuous output values. This is particularly true in scenarios where the output is noisy and may assume various values (multi modal). By treating the problem as classification over discrete bins, we can obtain an approximate distribution over these bins, rather than settling for a single, averaged value as regression would yield. This approach not only facilitates sampling but may also lead to more favorable loss landscapes. The linked paper in this comment provides more details of this idea.

Re: Chronos: Learning the Language of Time Series

#24
post #11
post #3

I do not have a horse in the race, but it is interesting to see open source comparisons to traditional timeseries strategies: https://github.com/Nixtla/nixtla/tree/main/experiments/amazo... In general, the M-Competitions ( https://forecasters.org/resources/time-series-data/ ), the olympics of timeseries forecasting, have proven frustrating for ML methods... linear models do shockingly well and the ML models that have…

They are comparing a non-ensembled transformer model with an ensemble of simple linear models. It's not surprising that the ensemble models of linear time series models will do well, since ensembles optimize for the bias-variance trade-off. Transformer/ML models by themselves have a tendency to overfit past patterns. They pick up more signal in the patterns, but they also pick up spurious patterns. They're low bias b…

> ensemble of transformer models

Isn't that just dropout?

Re: Chronos: Learning the Language of Time Series

#25

Maybe I'm missing something obvious, but what is the idea behind quantizing and tokenizing time series? We tokenize text because text isn't numbers. In the case of time series, we're... turning numbers into less precise numbers? The benefit of scaling and centering is trivial and i guess all timeseries ML does it, but I don't see why we need a token after that.

Tokenisation turns a continuous signal into a normalized discrete vocabulary: stock "went up a lot", "went up a little", "stayed flat". This smooths out noise and simplifies matching up similar but not identical signals.

> We tokenize text because text isn't numbers.

Text is actually numbers. People tried inputting UTF8 directly into transformers, but it doesn't work that well. Karpathy explains why:

https://www.youtube.com/watch?v=zduSFxRajkE

Re: Chronos: Learning the Language of Time Series

#28

Maybe I'm missing something obvious, but what is the idea behind quantizing and tokenizing time series? We tokenize text because text isn't numbers. In the case of time series, we're... turning numbers into less precise numbers? The benefit of scaling and centering is trivial and i guess all timeseries ML does it, but I don't see why we need a token after that.

I'm building upon insights from this paper ( https://arxiv.org/pdf/2403.03950.pdf ) and believe that classification can sometimes outperform regression, even when dealing with continuous output values. This is particularly true in scenarios where the output is noisy and may assume various values (multi modal). By treating the problem as classification over discrete bins, we can obtain an approximate distribution over…

Isn't it a given that classification would "outperform" regression, assuming n_classes (It depends on what you mean by "outperform" since metrics for classification and regression aren't always comparable, but I think I'm following the meaning of your comment overall)

Re: Chronos: Learning the Language of Time Series

#29

Maybe I'm missing something obvious, but what is the idea behind quantizing and tokenizing time series? We tokenize text because text isn't numbers. In the case of time series, we're... turning numbers into less precise numbers? The benefit of scaling and centering is trivial and i guess all timeseries ML does it, but I don't see why we need a token after that.

Tokenisation turns a continuous signal into a normalized discrete vocabulary: stock "went up a lot", "went up a little", "stayed flat". This smooths out noise and simplifies matching up similar but not identical signals. > We tokenize text because text isn't numbers. Text is actually numbers. People tried inputting UTF8 directly into transformers, but it doesn't work that well. Karpathy explains why: https://www.yout…

Interesting. Can you explain how this is superior and/or different from traditional DSP filters or other non-tokenization tricks in the signal processing field?
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