Time Series Forecasting Gets a Knowledge Boost

Author: Denis Avetisyan


A new framework, TiMi, combines the power of transformer networks with textual insights to dramatically improve the accuracy of predictions.

TiMi establishes a time series modeling approach wherein large language models infer future trends from textual content, and a Mixture-of-Experts module integrates this causal knowledge with historical data to provide a comprehensive global view for enhanced prediction.
TiMi establishes a time series modeling approach wherein large language models infer future trends from textual content, and a Mixture-of-Experts module integrates this causal knowledge with historical data to provide a comprehensive global view for enhanced prediction.

TiMi leverages a Mixture of Experts architecture and integrates causal knowledge from text to achieve state-of-the-art multimodal time series forecasting.

While leveraging multiple data sources promises more accurate time series forecasting, effectively integrating diverse modalities-particularly text conveying causal influences-remains a significant challenge. This paper introduces ‘TiMi: Empower Time Series Transformers with Multimodal Mixture of Experts’, a novel framework that harnesses the reasoning capabilities of large language models to guide transformer-based time series predictions. By employing a Mixture-of-Experts module, TiMi seamlessly integrates both textual and numerical data without requiring explicit alignment, achieving state-of-the-art performance on multiple benchmarks. Could this approach unlock new levels of interpretability and accuracy in forecasting complex, real-world phenomena?


Beyond Singular Data Streams: The Limitations of Traditional Forecasting

Historically, time series forecasting has been heavily dependent on quantitative data – past sales figures, stock prices, or temperature readings – often overlooking the wealth of qualitative, contextual information that shapes future events. This narrow focus creates a significant limitation, as real-world phenomena are rarely driven by numerical trends in isolation; instead, they are frequently influenced by external factors such as news reports, social media sentiment, policy changes, or even seemingly unrelated events. By neglecting these contextual cues, traditional models risk producing inaccurate or incomplete predictions, particularly in dynamic environments where non-numerical information plays a crucial role in shaping outcomes. The inherent assumption that the past strictly dictates the future, without acknowledging the influence of surrounding circumstances, ultimately restricts the predictive power of these established techniques.

Conventional time series forecasting, while effective in stable conditions, often falters when confronted with the intricacies of real-world events. These models frequently operate under the assumption of stationarity – that past patterns will continue into the future – an assumption easily broken by unforeseen circumstances. Complex systems, such as financial markets or consumer behavior, are inherently susceptible to external shocks – geopolitical events, shifts in public sentiment, or even viral trends – that exert considerable influence on outcomes. When these factors are ignored, forecasts become increasingly unreliable, failing to account for the non-linear dynamics and interconnectedness that characterize these systems. Consequently, a reliance solely on historical numerical data provides an incomplete picture, hindering accurate predictions in environments shaped by a multitude of constantly evolving influences.

The proliferation of digital communication has unlocked unprecedented access to textual data – news articles, social media posts, analyst reports, and more – representing a potentially powerful supplement to traditional numerical forecasting. While historical data often reveals what happened, these textual sources frequently contain insights into why it happened, and crucially, signals regarding future events before they are reflected in quantitative metrics. However, effectively harnessing this information presents significant hurdles; simply adding text as another variable often proves ineffective. The challenge lies in transforming unstructured, often ambiguous language into actionable insights, requiring sophisticated natural language processing techniques to extract relevant themes, assess sentiment, and ultimately, translate qualitative information into quantifiable predictors that can improve forecasting models across diverse fields, from financial markets to public health.

Real-world forecasting often involves multimodal time series data, where series-metadata exhibits semantic alignment unlike series-textual data, which, despite lacking direct alignment, can provide more insightful predictive information.
Real-world forecasting often involves multimodal time series data, where series-metadata exhibits semantic alignment unlike series-textual data, which, despite lacking direct alignment, can provide more insightful predictive information.

Fusion Strategies: Architecting Data Integration for Enhanced Prediction

Early fusion techniques, also known as feature-level fusion, involve concatenating raw data from multiple modalities into a single input vector prior to any significant processing. While computationally efficient, this approach can result in the loss of unique characteristics inherent to each individual modality. Specifically, the direct combination of features may dilute distinct signals, obscure modality-specific patterns, and introduce noise, particularly if the modalities have vastly different scales or statistical distributions. This can hinder the model’s ability to effectively learn and utilize the information contained within each modality, ultimately impacting predictive performance compared to strategies that preserve modality-specific representations for a longer duration in the processing pipeline.

Late fusion strategies in multi-modal data analysis involve independent processing of each modality’s feature extraction and prediction stages. This approach generates separate predictions for each modality, which are then combined – typically through averaging, weighted averaging, or a learned combination function – to produce a final prediction. While late fusion offers increased flexibility as each modality can utilize optimal, modality-specific algorithms, it may fail to capture complex, early-stage interactions between the input data streams that could contribute to improved predictive performance. The combination function itself introduces a parameter set that requires training and optimization to effectively leverage the individual modality predictions.

Deep learning architectures, specifically those employing techniques like convolutional neural networks (CNNs), recurrent neural networks (RNNs), and transformers, facilitate the implementation of both early and late fusion strategies. These architectures allow for the creation of models capable of processing data from multiple modalities – such as image, text, and audio – and learning complex, non-linear relationships between them. Attention mechanisms within these architectures enable the model to focus on the most relevant features across modalities, improving predictive performance. Furthermore, techniques like multi-modal embeddings create a shared representation space where data from different sources can be directly compared and integrated, allowing the model to capture cross-modal interactions that would be lost in simpler approaches. The flexibility of deep learning allows for custom architectures tailored to specific fusion requirements, enabling researchers to explore various methods for combining and leveraging multi-modal data.

Multimodal time series forecasting models can be categorized by their fusion approach, distinguishing how they integrate information from multiple data sources.
Multimodal time series forecasting models can be categorized by their fusion approach, distinguishing how they integrate information from multiple data sources.

TiMi: A Novel Framework for Orchestrating Multimodal Forecasting

TiMi employs a novel architecture for multimodal time series forecasting by integrating Large Language Models (LLMs) with a Mixture of Experts (MoE) framework. The LLM component provides the capacity for complex pattern recognition and contextual understanding, while the MoE layer allows the model to specialize in different aspects of the multimodal data. Specifically, the MoE distributes the processing of input features across multiple expert networks, each trained to handle specific data characteristics or time series patterns. This division of labor enhances the model’s ability to capture nuanced relationships within and between modalities, leading to improved forecasting accuracy compared to traditional approaches. The combination enables TiMi to effectively leverage the strengths of both LLMs and specialized expert networks for robust multimodal time series prediction.

The TiMi framework utilizes the Transformer architecture to process time series data by initially applying the Patchify technique, which divides the input time series into smaller, manageable segments or “patches.” These patches are then treated as tokens, analogous to words in natural language processing, allowing the Transformer’s self-attention mechanism to identify temporal dependencies and relationships within the time series. This approach enables robust feature extraction by capturing both local and global patterns, and facilitates parallel processing for improved computational efficiency. The resulting feature representations are then utilized for forecasting, offering a significant improvement over traditional recurrent or convolutional methods in capturing complex temporal dynamics.

TiMi employs a non-fusion guidance mechanism whereby textual data influences time series forecasting without requiring direct concatenation or merging of the modalities. This is achieved through a conditional generation process where the time series model is steered by textual inputs, allowing it to leverage external information without compromising the inherent statistical properties of the time series data. Evaluated on sixteen real-world multimodal time series forecasting benchmarks, TiMi consistently demonstrates state-of-the-art performance, exceeding existing methods in predictive accuracy and robustness across diverse datasets.

TiMi surpasses baseline models, including IMM-TSF and PatchTST, in forecasting irregular multimodal time series on the Time-IMM datasets, indicating its superior ability to integrate irregular textual data.
TiMi surpasses baseline models, including IMM-TSF and PatchTST, in forecasting irregular multimodal time series on the Time-IMM datasets, indicating its superior ability to integrate irregular textual data.

Navigating Risks and Expanding Horizons: The Future of Multimodal Forecasting

A significant challenge in multimodal forecasting lies in preventing data leakage, a phenomenon where information from the future inadvertently influences model training and evaluation. This can create a misleadingly positive assessment of a model’s capabilities, as it appears to predict outcomes it has already, in effect, ‘seen’. Rigorous methodologies are therefore essential to isolate the predictive power of the model from spurious correlations arising from improperly sequenced data. Specifically, careful attention must be paid to the temporal ordering of features, ensuring that only information available at the time of prediction is used during training and testing phases. Failing to address data leakage results in overly optimistic performance estimates that do not generalize to real-world scenarios, hindering the reliable deployment of forecasting models.

Beyond statistical correlations, integrating causal knowledge into forecasting models offers a pathway to more robust and reliable predictions. By explicitly representing the underlying mechanisms driving time series data – understanding why certain events precede others – models can move beyond simply recognizing patterns to genuinely understanding the system. This approach allows for improved accuracy, particularly when faced with shifts in data distribution or unforeseen circumstances, because the model isn’t solely reliant on previously observed correlations. Instead, it leverages an understanding of cause-and-effect relationships, enabling it to generalize effectively to scenarios outside of its training data and ultimately make more informed predictions about future outcomes.

The forecasting of real-world data often involves irregular time series – data points recorded at uneven intervals – presenting a significant modeling hurdle. TiMi’s architecture addresses this challenge directly, exhibiting robust performance on such datasets. Evaluations conducted on a held-out test set spanning July 2023 to May 2024 consistently demonstrate TiMi’s superior predictive accuracy compared to existing methods. Crucially, these results suggest the improvements stem from the model’s inherent design – its ability to effectively process and learn from irregularly spaced data – rather than simply memorizing patterns within the training set. This capacity for generalization is vital for reliable forecasting in dynamic, real-world scenarios where consistent, evenly spaced data is rarely available.

Replacing the large language model (LLM) backbone with alternative architectures affects multimodal time series forecasting performance, as demonstrated by average results across four datasets and prediction horizons (see Appendix H.3 for details).
Replacing the large language model (LLM) backbone with alternative architectures affects multimodal time series forecasting performance, as demonstrated by average results across four datasets and prediction horizons (see Appendix H.3 for details).

The architecture of TiMi, as presented in this work, underscores a fundamental principle of systemic design. The framework’s integration of textual information-its ‘causal knowledge’-into the time series forecasting process isn’t merely additive, but transformative. This echoes a holistic approach, recognizing that altering one component-in this case, incorporating external knowledge-necessitates a comprehensive understanding of the entire system. As Claude Shannon observed, “The most important thing in communication is to get the message across.” TiMi achieves precisely that; it doesn’t just forecast numbers, but transmits understanding by contextualizing those numbers within a richer, multimodal framework. The Mixture of Experts architecture allows the model to dynamically select and prioritize relevant knowledge, mirroring the elegance of a well-tuned system where structure dictates behavior and minimizes noise.

Beyond Prediction

The integration of textual data, as demonstrated by TiMi, represents a necessary, if predictable, progression. The field has long pursued increasingly complex architectures, often mistaking computational sophistication for genuine understanding. TiMi correctly identifies that the structure of causal knowledge, when properly encoded, can significantly improve forecasting – a welcome emphasis on first principles. However, the reliance on large language models introduces familiar dependencies. The true cost of this “freedom” from hand-engineered features is a considerable computational burden and an opacity that hinders interpretability. Scaling such models will inevitably reveal new bottlenecks, not necessarily in the architecture itself, but in the data pipelines required to sustain them.

Future work must address the limitations inherent in treating text as a mere input feature. The challenge isn’t simply to include causal knowledge, but to create systems capable of reasoning with it. A model that merely correlates textual cues with time series behavior will always be brittle. The next iteration should focus on developing mechanisms for validating and refining this knowledge, perhaps through active learning or by grounding the textual representations in a more robust symbolic framework.

Ultimately, the pursuit of “state-of-the-art” performance is a distraction. Good architecture is invisible until it breaks. The real test of TiMi, and its successors, will be its ability to gracefully degrade under unforeseen circumstances – to reveal, not hide, its underlying assumptions. The elegance of a solution isn’t measured by its complexity, but by its ability to simplify the world, not merely reflect it.


Original article: https://arxiv.org/pdf/2602.21693.pdf

Contact the author: https://www.linkedin.com/in/avetisyan/

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2026-02-27 04:14