StratRAG

StratRAG is a retrieval evaluation dataset for benchmarking Retrieval-Augmented Generation (RAG) systems on multi-hop reasoning tasks. It is derived from HotpotQA (distractor setting) and structured specifically for evaluating retrieval strategies — including sparse (BM25), dense, and hybrid approaches — in realistic, noisy document pool conditions.

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Why StratRAG?

Most RAG benchmarks either evaluate end-to-end generation quality or assume clean, small document sets. StratRAG addresses a gap: retrieval evaluation under multi-hop, distractor-heavy conditions, where:

• Each question requires reasoning across 2 gold documents
• The retriever must find those 2 docs inside a pool of 15 candidates (13 distractors)
• Questions span 3 types: bridge, comparison, and yes-no

This makes it suitable for measuring Recall@k, MRR, NDCG, and faithfulness of retrieved context before any generation step.

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Dataset Structure

Splits

Split	Rows
train	2000
validation	200

Schema

{
  "id":               str,          # e.g. "train_000042"
  "query":            str,          # the multi-hop question
  "reference_answer": str,          # ground-truth answer string
  "doc_pool": [                     # always exactly 15 documents
    {
      "doc_id": str,                # globally unique doc identifier
      "text":   str,                # title + paragraph body
      "source": str,                # paragraph title (from HotpotQA)
    }
  ],
  "gold_doc_indices": [int],        # indices into doc_pool (always [0, 1])
                                    # gold docs are always placed first
  "metadata": {
    "split":         str,           # "train" or "val"
    "question_type": str,           # "bridge" | "comparison" | "yes-no"
  },
  "created_at": str,                # ISO-8601 UTC timestamp
  "provenance": {
    "base": str,                    # "hotpot_qa(distractor)"
    "seed": int,                    # 42
  }
}

Key design decisions

• Gold docs are always at indices 0 and 1 in doc_pool. This makes it trivial to compute oracle retrieval metrics and verify your retriever's upper bound.
• 13 distractor documents per row are drawn from HotpotQA's built-in distractor paragraphs — these are topically related and intentionally difficult to distinguish from gold docs.
• Empty-text paragraphs are filtered out — HotpotQA contains some paragraphs with no sentence content; these are excluded from distractor slots to ensure all 15 docs have real text.

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Usage

from datasets import load_dataset

ds = load_dataset("Aryanp088/StratRAG")

# Inspect a single training example
row = ds["train"][0]
print("Query:", row["query"])
print("Answer:", row["reference_answer"])
print("Question type:", row["metadata"]["question_type"])
print("Gold doc indices:", row["gold_doc_indices"])
print("Number of docs in pool:", len(row["doc_pool"]))

# Access gold documents directly
for idx in row["gold_doc_indices"]:
    print(f"\nGold doc [{idx}]:", row["doc_pool"][idx]["text"][:200])

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Evaluation Example

from datasets import load_dataset

ds = load_dataset("Aryanp088/StratRAG", split="validation")

def recall_at_k(row, k=2):
    """
    Simulate a retriever that returns the first k docs (random baseline).
    Replace retrieved_indices with your retriever's output.
    """
    retrieved_indices = list(range(k))   # replace with your retriever
    gold = set(row["gold_doc_indices"])
    hits = len(gold & set(retrieved_indices))
    return hits / len(gold)

scores = [recall_at_k(row, k=2) for row in ds]
print(f"Random Recall@2: {sum(scores)/len(scores):.3f}")  # ~0.133 (2/15)

To benchmark a real retriever (e.g. BM25):

from rank_bm25 import BM25Okapi

def bm25_recall_at_k(row, k=2):
    docs    = [doc["text"].split() for doc in row["doc_pool"]]
    query   = row["query"].split()
    bm25    = BM25Okapi(docs)
    scores  = bm25.get_scores(query)
    top_k   = sorted(range(len(scores)), key=lambda i: scores[i], reverse=True)[:k]
    gold    = set(row["gold_doc_indices"])
    return len(gold & set(top_k)) / len(gold)

scores = [bm25_recall_at_k(row, k=2) for row in ds]
print(f"BM25 Recall@2: {sum(scores)/len(scores):.3f}")

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Question Type Distribution

Type	Train	Validation
bridge	1775	171
yes-no	113	12
comparison	112	17

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Provenance & Reproducibility

All rows are derived from HotpotQA (distractor configuration) with seed=42.

from datasets import load_dataset
hotpot = load_dataset("hotpot_qa", "distractor")

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Benchmark Results

Evaluated on the validation split (n=200) using three retrieval strategies.

Overall Results

Retriever	Recall@1	Recall@2	Recall@5	MRR	NDCG@5
Random	0.0525	0.1425	0.3300	0.3190	0.2336
BM25	0.3950	0.6000	0.8150	0.8732	0.7624
Dense (MiniLM-L6-v2)	0.4175	0.6500	0.8600	0.9035	0.8087
Hybrid (BM25 + Dense)	0.4400	0.6975	0.9050	0.9310	0.8543

Hybrid retriever uses equal-weight (α=0.5) min-max normalized score fusion.

Hybrid Retriever — By Question Type

Question Type	n	Recall@2	MRR	NDCG@5
bridge	171	0.6696	0.9281	0.8418
comparison	17	0.8824	0.9706	0.9473
yes-no	12	0.8333	0.9167	0.9007

Key findings:

• Hybrid retrieval consistently outperforms sparse and dense individually across all metrics
• Dense retrieval outperforms BM25 on all metrics, highlighting the importance of semantic matching for multi-hop questions
• Bridge questions are the hardest retrieval type (Recall@2 = 0.67), as they require cross-document reasoning without strong lexical overlap
• Comparison and yes-no questions benefit more from BM25's keyword matching (higher Recall@2)
• Recall@5 of 0.905 for Hybrid shows that 90% of the time, both gold documents appear in the top 5 — a strong upper bound for downstream generation

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Limitations

• English only — inherited from HotpotQA
• Wikipedia-domain — all documents are Wikipedia paragraphs; may not generalize to other domains without adaptation
• 2,200 total rows — suitable for retriever evaluation and fine-tuning signal, not large-scale pretraining
• Gold position is fixed — gold docs are always at indices 0 and 1. Shuffle doc_pool before training retrievers to avoid position bias

import random
random.shuffle(row["doc_pool"])   # shuffle before use in training

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Citation

If you use StratRAG in your work, please cite:

@dataset{patodiya2026stratrag,
  author    = {Patodiya, Aryan},
  title     = {StratRAG: A Multi-Hop Retrieval Evaluation Dataset for RAG Systems},
  year      = {2026},
  publisher = {Hugging Face},
  url       = {https://huggingface.co/datasets/Aryanp088/StratRAG}
}

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Author

Aryan Patodiya — ML Systems Engineer
MS Computer Science @ California State University, Fresno
Portfolio · GitHub · aryanpatodiya018@gmail.com