Wrong Answers from RAG

The Problem

Retrieved context is relevant but AI generates factually incorrect answers, misinterprets the context, or combines information incorrectly.

Symptoms

• ❌ Context has right info, answer is wrong

• ❌ Misreads numbers, dates, names

• ❌ Reverses cause and effect

• ❌ Combines facts from different contexts incorrectly

• ❌ Ignores critical qualifiers ("not", "except")

Real-World Example

Retrieved context:
"Enterprise plan costs $500/month. Basic plan costs $50/month."

User query: "How much is the basic plan?"

AI response: "The Basic plan costs $500 per month."

Problem: Confused Enterprise and Basic pricing
Context was correct, interpretation wrong

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Deep Technical Analysis

Semantic Confusion

Similar Entity Names:

Context: "Product A supports 10 users. Product B supports 100 users."
Query: "How many users does Product B support?"
AI: "Product B supports 10 users."

LLM confused A and B (single character difference)

Negation Handling:

Context: "Feature X is NOT available in the free tier."
Query: "Is feature X in free tier?"
AI: "Yes, feature X is available in the free tier."

LLM missed "NOT" - critical negation ignored

Context Assembly Issues

Conflicting Chunks:

Chunk 1: "Rate limit is 100 requests/hour"
Chunk 2: "New rate limit (as of Jan 2024): 1000 requests/hour"

Both retrieved, but Chunk 1 ranked higher:
→ AI uses outdated information
→ Wrong answer despite correct info present

Partial Context:

Full doc: "API key authentication required for all endpoints except /health"

Retrieved chunk: "API key authentication required for all endpoints"
→ Critical exception cut off by chunking boundary
→ AI gives incomplete answer

LLM Reasoning Errors

Multi-Hop Reasoning:

Context:
- "UserA has access to ProjectX"
- "ProjectX contains DocumentY"

Query: "Can UserA access DocumentY?"

Requires inference:
UserA → ProjectX → DocumentY = Yes

LLM may fail to chain the reasoning:
→ "I don't have information about UserA accessing DocumentY"

Quantitative Errors:

Context: "Increased by 25% from previous quarter (1000 units to 1250)"

Query: "What was the increase?"

AI: "The increase was 250 units (25%)"
→ Should be 1250 units
→ Confuses percent with absolute value

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How to Solve

Implement reranking to surface most relevant context first + use chain-of-thought prompting for multi-step reasoning + add explicit negation handling in prompts + apply answer validation (fact-checking against context) + use higher-quality models (GPT-4 over GPT-3.5) for complex interpretation + test with eval set of tricky questions. See Answer Quality.