The Decision Flowchart: Combining Both Axes (Including the Hybrid Case)

~12 min read

Putting the two independent axes together into one concrete decision path — including the fourth quadrant, where both knowledge and behavior need to change, calling for a hybrid RAG + fine-tuning approach.

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Key points

  • Two independent axes drive the whole decision: external knowledge needed, and behavioral adaptation needed
  • Low/Low -> prompting. High knowledge/Low adaptation -> RAG. Low knowledge/High adaptation -> fine-tuning
  • High/High (the 4th quadrant) needs a hybrid approach — neither RAG nor fine-tuning alone closes both gaps
  • The hybrid typically means fine-tuning for consistent behavior/vocabulary, plus RAG for the custom (often changing) knowledge base
  • Practical procedure: check knowledge need first, then behavior need, and plan for hybrid upfront if both are true rather than discovering it midway