Literature Review – Case Study
The “Doing Business” Mistake: When LLMs Hallucinate Literature Reviews
🏛️ Organization: World Bank IEG & IFAD
🤖 Models: ChatGPT (GPT-3.5), GPT-4o, GPT-4o-mini
📋 Topic: Doing Business Indicators → Epidemic Preparedness
📘 Original 2023 Blog: Setting up Experiments
⚠️ “Unfulfilled Promises” – The Failure Blog
What happened in the 2023 experiment?
The setup
As part of eight limited experiments published as a blog series in August 2023, the IEG team tested whether LLMs could assist with evaluation tasks. One of the two use cases that yielded “unimpressive results” was the Structured Literature Review (SLR). The team asked both ChatGPT and the World Bank’s enterprise version mAI (powered by GPT-3.5 via Microsoft) to conduct a literature review using this prompt:
The research topic was the World Bank’s Doing Business Indicators—a well-documented set of metrics that had already been the subject of a previous IEG SLR. This gave the team a “ground truth” to compare against.
What the models produced
✅ What worked
- Both ChatGPT and mAI provided plausible responses that overlapped with IEG’s previously completed robust SLR on this topic
- ChatGPT provided a quite long and detailed response
- The high-level insights were thematically appropriate
❌ What failed
- Many references were entirely made up (hallucinated) — they sounded like real journal articles, but a web search yielded no results
- Using the ScholarAI plug-in did not fix the issue
- The model could not distinguish between real and fabricated citations
📌 Verdict (as of 2023):
“We do not recommend using these tools to conduct a literature review. However, they can still be used — with caution — to obtain background knowledge on a specific topic.”
What should the experts have done differently?
The 2023 experiment failed not because LLMs are incapable of supporting literature reviews, but because the experts asked the wrong question in the wrong way. Here is a systematic critique of their methodology, contrasted with the approach later validated in the 2025 guidance note.
❌ Mistake #1: Treating the LLM as a Junior Analyst Instead of a Component
What they did: Gave the model an end-to-end task: “write a literature review.” This is like asking an intern to “build a house” rather than “hammer these nails.”
✅ What they should have done: Break the SLR into modular, verifiable subtasks: (1) text classification, (2) information extraction, (3) summarization, (4) synthesis. The 2025 guidance note states: “For complex use cases such as SLRs, it is important to unpack the various analytical steps.”
❌ Mistake #2: No Ground Truth, No Validation Set, No Testing
What they did: Compared the LLM’s output to a “previously completed robust SLR” but did not establish systematic metrics. They did not split documents into training, validation, and testing sets.
✅ What they should have done: Follow the 2025 protocol of dividing the dataset into four distinct sets: Training (~5 documents for examples), Validation (~20 for prompt refinement), Testing (~30 for unbiased assessment), Prediction (remaining unlabeled). Without this structure, they had no way to measure recall, precision, or F1 scores.
❌ Mistake #3: Blind Trust in Reference Generation
What they did: Asked the model to generate a reference list and were surprised when the references were fake. Even the ScholarAI plug-in did not solve the problem.
✅ What they should have done: Recognize that LLMs are not databases. The 2025 guidance note advises: “Provide ‘unknown’ or ‘not applicable’ as a category… Include a request for references to the source document(s).” Better yet, use retrieval-augmented generation (RAG) and never ask the model to generate citations from memory.
❌ Mistake #4: No Iterative Prompt Refinement
What they did: Ran the prompt once (or a few times) and declared the approach unsuccessful.
✅ What they should have done: Treat prompt development as an iterative scientific process. The 2025 guidance note describes a “prompting and validation loop”: start with basic prompt → apply to validation set → measure performance → refine based on error patterns → repeat until satisfactory → then apply to test set.
❌ Mistake #5: No Human-in-the-Loop Validation
What they did: Treated the LLM’s output as a final product, then discovered hallucinations after the fact.
✅ What they should have done: Design workflows with mandatory human checkpoints. The 2025 guidance note is unambiguous: “The manual review component is mandatory in our workflows when LLM or machine learning are used.”
How the 2024 experiments fixed the approach
The 2025 guidance note explicitly states: “We chose to focus on one of the two use cases that had yielded unimpressive results: SLRs.” The follow-up experiments in late 2024 (over a two-month period) built on the 2023 failure by testing LLMs on specific components of SLRs rather than the full task. The new use case was an ongoing IEG thematic evaluation of the World Bank Group’s support for epidemic preparedness.
The four experiments
Results: What worked and what didn’t
📊 Text Classification
Accuracy: 0.90 | Recall: 0.75 | Precision: 0.60 | F1: 0.67
“Strong results after multiple iterations to refine the prompt using the validation set.”
📝 Text Summarization
Faithfulness: 0.90 | Relevance: 4.87/5 | Coherence: 4.97/5
“Abstracts generated contained the most important information, often outperforming original abstracts.”
🔍 Information Extraction
Faithfulness: 1.00 | Relevance: 3.25/5
“Model had difficulty extracting the most relevant information… omissions of relevant information were noted.”
🔄 Text Synthesis
Faithfulness: 1.00 | Relevance: 4.20/5 | Coherence: 5.00/5
“No hallucinations took place. However, some relevant information was omitted.”
🔬 Critical finding:
The 2024 experiments achieved no hallucinations in any generative task (summarization, synthesis, extraction). The relevance score for extraction (3.25/5) was the only weak point. This demonstrates that breaking tasks into modular components with rigorous validation eliminated the hallucination problem that plagued the 2023 end-to-end approach.
Key lessons for evaluators
📌 Modularity is mandatory
Never ask an LLM to do end-to-end what you can break into verifiable components. The 2025 guidance note emphasizes: “It is important to unpack the various analytical steps and to carefully examine for what and how LLMs can be leveraged.”
📊 Validate with metrics
Use recall, precision, F1 for classification; faithfulness, relevance, coherence for generative tasks. Set context-specific thresholds. The 2025 team deemed recall >0.6 and precision >0.7 as “satisfactory” for their SLR context.
👥 Humans must stay in the loop
The guidance note is explicit: “The manual review component is mandatory in our workflows when LLM or machine learning are used.” No exceptions.
🎯 Representative sampling
Use text clustering to identify ~55 representative documents. Include ~5 in training, ~20 in validation, ~30 in testing. This ensures semantic diversity and avoids biased performance metrics.
The bottom line
The 2023 experiment failed not because LLMs are incapable of supporting literature reviews, but because the experts asked the wrong question in the wrong way.
Bad question: “Can an LLM write a literature review?”
Good question: “Which components of a literature review can an LLM perform reliably, and how do we validate each component?”
By 2025, the same team had transformed failure into a rigorous framework—proving that with proper methodology, LLMs can achieve 90% accuracy, perfect faithfulness, and zero hallucinations on modular SLR tasks.
Frequently asked questions
Why did the 2023 experiment fail so spectacularly?
Because it violated nearly every principle of robust LLM integration: it asked for an end-to-end task without modular breakdown, had no validation sets or metrics, trusted the model to generate references from memory, skipped iterative prompt refinement, and excluded mandatory human review. The 2025 guidance note explicitly warns against this approach.
Did the 2024 experiments completely solve the hallucination problem?
For the tasks tested (classification, summarization, synthesis, extraction), yes—faithfulness scores were 0.90-1.00 with zero hallucinations. However, the relevance score for information extraction (3.25/5) showed that completeness remains a challenge. The 2025 guidance note acknowledges: “Challenges remain in ensuring completeness and relevance in information extraction and text synthesis tasks.”
Can I use LLMs for literature reviews today?
Yes—but only for specific components (classification, summarization, extraction) with rigorous validation protocols. Do NOT ask an LLM to write an end-to-end literature review with citations from memory. Use retrieval-augmented generation (RAG), provide source documents, include “unknown” as a category, and always validate with human review on a representative sample.
What metrics should I use to evaluate LLM performance on literature review tasks?
For classification: accuracy, recall, precision, F1, balanced accuracy. For summarization and synthesis: faithfulness (0/1 scale), relevance (1-5 Likert), coherence (1-5 Likert). Always measure intercoder reliability (Cohen’s kappa) for human annotations. Set context-specific thresholds based on the stakes of your use case.
Main reference & original sources
📘 Primary source: Anuj, H., Den Boer, H., & Raimondo, E. (2025). Balancing Innovation and Rigor: Guidance for the Thoughtful Integration of Artificial Intelligence for Evaluation. World Bank Independent Evaluation Group & IFAD Independent Office of Evaluation.
🔗 Download the full guidance note (PDF)
📘 Original 2023 blog series:
• Setting up Experiments to Test GPT for Evaluation (August 16, 2023)
• Fulfilled Promises: Using GPT for Analytical Tasks (August 23, 2023)
• Unfulfilled Promises: Using GPT for Synthetic Tasks (August 30, 2023)
Resources for further learning
- 📄 IEG Guidance Note (PDF)
- 📘 IEG Blog: Experiment Setup
- 🎓 EvalCommunity – AI in M&E Course
- 🔧 DAIR.AI Prompt Engineering Guide
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