RAG or Finetuning: Which Route Should Your NLP Model Take?

In the realm of machine learning and Natural Language Processing (NLP), the challenge of augmenting models for specific tasks has always been a subject of ongoing research and debate. Two prominent methodologies for this augmentation are Retrieval-Augmented Generation (RAG) and model finetuning. Both of these techniques come with their own sets of benefits and drawbacks. In this blog post, we will explore each method in depth to understand when to use which technique for better outcomes.

What is Retrieval-Augmented Generation (RAG)?

Retrieval-Augmented Generation is a paradigm in which a text generation model uses an external database or knowledge source to “retrieve” relevant information, which it then incorporates into its responses. Essentially, a retrieval model scans through a corpus to find pertinent text segments, and then a generation model takes this information into account when generating a reply. This mechanism often improves the model’s capability to provide contextually accurate and information-rich answers.

Pros of RAG

1. Information Richness: RAG models can pull in factual data, statistics, or examples, providing a level of detail that a standalone model may not achieve.
2. Dynamic Learning: Without needing to be retrained, RAG models can adapt to new data as long as the retrieval corpus is updated.
3. Less Risk of Memorization: Since they pull from an external database, RAG models are less likely to incorrectly memorize and regurgitate data.
4. Less Prone to Hallucination: Since they furnish evidence of the response.

Cons of RAG

1. Computational Cost: Scanning through large databases can be computationally expensive and slow.
2. Inconsistency: The model might retrieve conflicting information, leading to inconsistent or incoherent outputs.
3. Dependence on External Data: The quality of the generated output is highly dependent on the quality and breadth of the retrieval corpus.

What is Model Finetuning?

Finetuning is the process of taking a pre-trained machine learning model and continuing its training on a specific dataset that is closely related to the task at hand. This not only cuts down on training time but also leverages the extensive learning the model has already undergone.

Pros of Finetuning

1. Task-Specific Optimization: The model becomes highly specialized for the task it is finetuned for.
2. Quicker Deployment: Finetuning usually requires less computational power and time compared to training a model from scratch.
3. Coherent Outputs: Since the model is trained end-to-end for a specific task, the outputs are generally more coherent and contextually appropriate.

Cons of Finetuning

1. Overfitting Risk: Overfitting to the specific dataset is a possibility if not carefully managed.
2. Inflexibility: Once finetuned, the model may not perform well on tasks that are even slightly different from the one it was specialized for.
3. Data Sensitivity: The quality of the finetuning data is crucial. Any biases or errors in the dataset may be magnified during the finetuning process.

When to Use Which?

1. For General-Purpose Tasks: If the task at hand is general and does not require specialized knowledge, using a RAG model may be more beneficial as it can pull in information dynamically.
2. For Niche or Specialized Tasks: If the task is highly specific, finetuning is usually the better choice as it allows the model to specialize in that particular domain.
3. For Speed and Efficiency: If computational resources are a constraint, finetuning can often be more efficient.
4. For Dynamic Environments: In situations where the data landscape is constantly evolving, a RAG model can adapt more easily without requiring constant retraining.
5. Hybrid Approaches: In some cases, a combination of both RAG and finetuning can be applied for optimized performance.

Both Retrieval-Augmented Generation (RAG) and Model Finetuning are valuable techniques in machine learning and natural language processing (NLP) with a variety of practical use-cases.

Practical Use-Cases of RAG:

1. Search Engines: RAG models can help produce more relevant and contextual search results by pulling information from a large corpus.
2. Question-Answering Systems: In a QA system, RAG can retrieve relevant data or previous answers to generate more informative and contextually accurate responses.
3. Content Recommendation: RAG can help in suggesting articles, videos, or products based on their relevance to the user query, by dynamically fetching data from various sources.
4. Chatbots: For conversational agents that need to provide data-driven answers or recommendations, RAG can provide an information-rich and contextual experience.
5. Text Summarization: RAG can be used to pull in external information to create more comprehensive and informative summaries.
6. Medical Diagnosis Support: In healthcare, RAG models can pull in relevant medical literature or clinical guidelines to aid in the diagnosis or treatment planning.
7. Legal Research: Lawyers could use RAG-based systems to pull in relevant case law or statutes when preparing for cases.
8. Educational Tools: RAG can improve educational software by dynamically pulling in explanatory content or examples from a large corpus of educational material.

Practical Use-Cases of Finetuning:

1. Sentiment Analysis: Finetuning can specialize a general-purpose model for more accurate sentiment classification in specific industries like finance, healthcare, or consumer products.
2. Named Entity Recognition: For niche domains such as biomedical research, finetuning can help identify specific types of entities that a general-purpose model might miss.
3. Machine Translation: Models can be finetuned for specific language pairs or specialized vocabulary, like legal or medical terms.
4. Speech Recognition: Finetuning can improve the accuracy of speech recognition systems for specific accents, dialects, or noisy environments.
5. Text Classification: In content moderation or spam filtering, finetuning can make models more sensitive to the nuances of the specific kind of content being dealt with.
6. Customer Support: Customer support bots can be finetuned on a specific company’s products or policies to provide more accurate and relevant support.
7. Financial Forecasting: Finetuning can adapt models to better interpret financial market trends or company-specific data.
8. Autonomous Vehicles: Finetuning can optimize pre-trained models for specific driving conditions like night driving, snowy conditions, etc.

Hybrid Use-Cases:

In some scenarios, a combination of both RAG and Finetuning might be useful.

1. Personalized Healthcare: A finetuned model could be used for the specialized task of medical history intake, and a RAG model could be used to dynamically pull in the latest research or guidelines.
2. News Aggregation: Finetuned models could classify and prioritize news, while a RAG model pulls in additional context or relevant stories.
3. E-commerce: Finetuned models could handle the personalized recommendation of products, while RAG models could dynamically pull in reviews or specs.

By understanding the specific strengths and limitations of both RAG and Finetuning, organizations can better decide which approach to use for different applications.

Conclusion & Further Reading

Both Retrieval-Augmented Generation and model finetuning have their own sets of advantages and drawbacks, and the best method to use depends on a variety of factors including the task specificity, computational resources, and data quality. A nuanced understanding of both methodologies can help researchers and practitioners make more informed decisions, potentially even combining the strengths of both approaches for optimized results. Below are some fantastic blogs to further dwell into the use-cases:-

https://towardsdatascience.com/rag-vs-finetuning-which-is-the-best-tool-to-boost-your-llm-application-94654b1eaba7

https://medium.com/@pandey.vikesh/should-you-prompt-rag-tune-or-train-a-guide-to-choose-the-right-generative-ai-approach-5e264043bd7d

 

Disclaimer:- This note was written by me ( Mayank Nauni) in my personal capacity. The opinions expressed in this article are solely my own and do not reflect the view of my employer or my preference towards any of the OEMs.