How do you evaluate a RAG system end to end, including RAGAS-style metrics?
PICTURE THIS: OVERFITTING
Simple meaning
Score retrieval (recall, MRR), then generation (faithfulness, context precision, answer relevancy).
WHY — Tokens instead of words?
LLMs use tokens (not full words) because it helps them:
question about RAG.
trade-offs, and what you would actually do on a GenAI / LLM project - not buzzwords.
Each piece maps to a number the network can learn.
Fixed pieces are what transformers expect as input.
STEPS — What happens with tokens?
Before the model can read a sentence, it goes through these steps:
- 1Score retrieval (recall, MRR),
then generation (faithfulness, context precision, answer relevancy).
- 2RAGAS-style pipelines use LLM
judges plus the retrieved set.
- 3Human spot checks remain
necessary because judges inherit model biases.
- 4Context mix
Attention looks at nearby tokens together.
- 5Next token
The model scores what should come next.
- 6Decode
IDs turn back into readable text.
EXAMPLE — See it in action
Let's see how a real sentence is tokenized (tokens may vary by model):
Note: Actual tokens and IDs depend on the tokenizer (e.g., GPT, Llama, etc.).
Key takeaway
Score retrieval (recall, MRR), then generation (faithfulness, context precision, answer relevancy). RAGAS-style pipelines use LLM judges plus the retrieved set.