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# Performance Evaluation Framework
This document provides comprehensive methodologies for evaluating chunking strategy performance and effectiveness.
## Evaluation Metrics
### Core Retrieval Metrics
#### Retrieval Precision
Measures the fraction of retrieved chunks that are relevant to the query.
```python
def calculate_precision(retrieved_chunks: List[Dict], relevant_chunks: List[Dict]) -> float:
"""
Calculate retrieval precision
Precision = |Relevant ∩ Retrieved| / |Retrieved|
"""
retrieved_ids = {chunk.get('id') for chunk in retrieved_chunks}
relevant_ids = {chunk.get('id') for chunk in relevant_chunks}
intersection = retrieved_ids & relevant_ids
if not retrieved_ids:
return 0.0
return len(intersection) / len(retrieved_ids)
```
#### Retrieval Recall
Measures the fraction of relevant chunks that are successfully retrieved.
```python
def calculate_recall(retrieved_chunks: List[Dict], relevant_chunks: List[Dict]) -> float:
"""
Calculate retrieval recall
Recall = |Relevant ∩ Retrieved| / |Relevant|
"""
retrieved_ids = {chunk.get('id') for chunk in retrieved_chunks}
relevant_ids = {chunk.get('id') for chunk in relevant_chunks}
intersection = retrieved_ids & relevant_ids
if not relevant_ids:
return 0.0
return len(intersection) / len(relevant_ids)
```
#### F1-Score
Harmonic mean of precision and recall.
```python
def calculate_f1_score(precision: float, recall: float) -> float:
"""
Calculate F1-score
F1 = 2 * (Precision * Recall) / (Precision + Recall)
"""
if precision + recall == 0:
return 0.0
return 2 * (precision * recall) / (precision + recall)
```
### Mean Reciprocal Rank (MRR)
Measures the rank of the first relevant result.
```python
def calculate_mrr(queries: List[Dict], results: List[List[Dict]]) -> float:
"""
Calculate Mean Reciprocal Rank
"""
reciprocal_ranks = []
for query, query_results in zip(queries, results):
relevant_found = False
for rank, result in enumerate(query_results, 1):
if result.get('is_relevant', False):
reciprocal_ranks.append(1.0 / rank)
relevant_found = True
break
if not relevant_found:
reciprocal_ranks.append(0.0)
return sum(reciprocal_ranks) / len(reciprocal_ranks)
```
### Mean Average Precision (MAP)
Considers both precision and the ranking of relevant documents.
```python
def calculate_average_precision(retrieved_chunks: List[Dict], relevant_chunks: List[Dict]) -> float:
"""
Calculate Average Precision for a single query
"""
retrieved_ids = {chunk.get('id') for chunk in retrieved_chunks}
relevant_ids = {chunk.get('id') for chunk in relevant_chunks}
if not relevant_ids:
return 0.0
precisions = []
relevant_count = 0
for rank, chunk in enumerate(retrieved_chunks, 1):
if chunk.get('id') in relevant_ids:
relevant_count += 1
precision_at_rank = relevant_count / rank
precisions.append(precision_at_rank)
return sum(precisions) / len(relevant_ids) if relevant_ids else 0.0
def calculate_map(queries: List[Dict], results: List[List[Dict]]) -> float:
"""
Calculate Mean Average Precision across multiple queries
"""
average_precisions = []
for query, query_results in zip(queries, results):
ap = calculate_average_precision(query_results, query.get('relevant_chunks', []))
average_precisions.append(ap)
return sum(average_precisions) / len(average_precisions) if average_precisions else 0.0
```
### Normalized Discounted Cumulative Gain (NDCG)
Measures ranking quality with emphasis on highly relevant results.
```python
def calculate_dcg(retrieved_chunks: List[Dict]) -> float:
"""
Calculate Discounted Cumulative Gain
"""
dcg = 0.0
for rank, chunk in enumerate(retrieved_chunks, 1):
relevance = chunk.get('relevance_score', 0)
dcg += relevance / np.log2(rank + 1)
return dcg
def calculate_ndcg(retrieved_chunks: List[Dict], ideal_chunks: List[Dict]) -> float:
"""
Calculate Normalized Discounted Cumulative Gain
"""
dcg = calculate_dcg(retrieved_chunks)
idcg = calculate_dcg(ideal_chunks)
if idcg == 0:
return 0.0
return dcg / idcg
```
## End-to-End RAG Evaluation
### Answer Quality Metrics
#### Factual Consistency
Measures how well the generated answer aligns with retrieved chunks.
```python
import spacy
from transformers import pipeline
class FactualConsistencyEvaluator:
def __init__(self):
self.nlp = spacy.load("en_core_web_sm")
self.nli_pipeline = pipeline("text-classification",
model="roberta-large-mnli")
def evaluate_consistency(self, answer: str, retrieved_chunks: List[str]) -> float:
"""
Evaluate factual consistency between answer and retrieved context
"""
if not retrieved_chunks:
return 0.0
# Combine retrieved chunks as context
context = " ".join(retrieved_chunks[:3]) # Use top 3 chunks
# Use Natural Language Inference to check consistency
result = self.nli_pipeline(f"premise: {context} hypothesis: {answer}")
# Extract consistency score (entailment probability)
for item in result:
if item['label'] == 'ENTAILMENT':
return item['score']
elif item['label'] == 'CONTRADICTION':
return 1.0 - item['score']
return 0.5 # Neutral if NLI is inconclusive
```
#### Answer Completeness
Measures how completely the answer addresses the user's query.
```python
def evaluate_completeness(answer: str, query: str, reference_answer: str = None) -> float:
"""
Evaluate answer completeness
"""
# Extract key entities from query
query_entities = extract_entities(query)
answer_entities = extract_entities(answer)
# Calculate entity coverage
if not query_entities:
return 0.5 # Neutral if no entities in query
covered_entities = query_entities & answer_entities
entity_coverage = len(covered_entities) / len(query_entities)
# If reference answer is available, compare against it
if reference_answer:
reference_entities = extract_entities(reference_answer)
answer_reference_overlap = len(answer_entities & reference_entities) / max(len(reference_entities), 1)
return (entity_coverage + answer_reference_overlap) / 2
return entity_coverage
def extract_entities(text: str) -> set:
"""
Extract named entities from text (simplified)
"""
# This would use a proper NER model in practice
import re
# Simple noun phrase extraction as placeholder
noun_phrases = re.findall(r'\b[A-Z][a-z]+(?:\s+[A-Z][a-z]+)*\b', text)
return set(noun_phrases)
```
#### Response Relevance
Measures how relevant the answer is to the original query.
```python
from sentence_transformers import SentenceTransformer
from sklearn.metrics.pairwise import cosine_similarity
class RelevanceEvaluator:
def __init__(self, model_name="all-MiniLM-L6-v2"):
self.model = SentenceTransformer(model_name)
def evaluate_relevance(self, query: str, answer: str) -> float:
"""
Evaluate semantic relevance between query and answer
"""
# Generate embeddings
query_embedding = self.model.encode([query])
answer_embedding = self.model.encode([answer])
# Calculate cosine similarity
similarity = cosine_similarity(query_embedding, answer_embedding)[0][0]
return float(similarity)
```
## Performance Metrics
### Processing Time
```python
import time
from dataclasses import dataclass
from typing import List, Dict
@dataclass
class PerformanceMetrics:
total_time: float
chunking_time: float
embedding_time: float
search_time: float
generation_time: float
throughput: float # documents per second
class PerformanceProfiler:
def __init__(self):
self.timings = {}
self.start_times = {}
def start_timer(self, operation: str):
self.start_times[operation] = time.time()
def end_timer(self, operation: str):
if operation in self.start_times:
duration = time.time() - self.start_times[operation]
if operation not in self.timings:
self.timings[operation] = []
self.timings[operation].append(duration)
return duration
return 0.0
def get_performance_metrics(self, document_count: int) -> PerformanceMetrics:
total_time = sum(sum(times) for times in self.timings.values())
return PerformanceMetrics(
total_time=total_time,
chunking_time=sum(self.timings.get('chunking', [0])),
embedding_time=sum(self.timings.get('embedding', [0])),
search_time=sum(self.timings.get('search', [0])),
generation_time=sum(self.timings.get('generation', [0])),
throughput=document_count / total_time if total_time > 0 else 0
)
```
### Memory Usage
```python
import psutil
import os
from typing import Dict, List
class MemoryProfiler:
def __init__(self):
self.process = psutil.Process(os.getpid())
self.memory_snapshots = []
def take_memory_snapshot(self, label: str):
"""Take a snapshot of current memory usage"""
memory_info = self.process.memory_info()
memory_mb = memory_info.rss / 1024 / 1024 # Convert to MB
self.memory_snapshots.append({
'label': label,
'memory_mb': memory_mb,
'timestamp': time.time()
})
def get_peak_memory_usage(self) -> float:
"""Get peak memory usage in MB"""
if not self.memory_snapshots:
return 0.0
return max(snapshot['memory_mb'] for snapshot in self.memory_snapshots)
def get_memory_usage_by_operation(self) -> Dict[str, float]:
"""Get memory usage breakdown by operation"""
if not self.memory_snapshots:
return {}
memory_by_op = {}
for i in range(1, len(self.memory_snapshots)):
prev_snapshot = self.memory_snapshots[i-1]
curr_snapshot = self.memory_snapshots[i]
operation = curr_snapshot['label']
memory_delta = curr_snapshot['memory_mb'] - prev_snapshot['memory_mb']
if operation not in memory_by_op:
memory_by_op[operation] = []
memory_by_op[operation].append(memory_delta)
return {op: sum(deltas) for op, deltas in memory_by_op.items()}
```
## Evaluation Datasets
### Standardized Test Sets
#### Question-Answer Pairs
```python
from dataclasses import dataclass
from typing import List, Optional
import json
@dataclass
class EvaluationQuery:
id: str
question: str
reference_answer: Optional[str]
relevant_chunk_ids: List[str]
query_type: str # factoid, analytical, comparative
difficulty: str # easy, medium, hard
domain: str # finance, medical, legal, technical
class EvaluationDataset:
def __init__(self, name: str):
self.name = name
self.queries: List[EvaluationQuery] = []
self.documents: Dict[str, str] = {}
self.chunks: Dict[str, Dict] = {}
def add_query(self, query: EvaluationQuery):
self.queries.append(query)
def add_document(self, doc_id: str, content: str):
self.documents[doc_id] = content
def add_chunk(self, chunk_id: str, content: str, doc_id: str, metadata: Dict):
self.chunks[chunk_id] = {
'id': chunk_id,
'content': content,
'doc_id': doc_id,
'metadata': metadata
}
def save_to_file(self, filepath: str):
data = {
'name': self.name,
'queries': [
{
'id': q.id,
'question': q.question,
'reference_answer': q.reference_answer,
'relevant_chunk_ids': q.relevant_chunk_ids,
'query_type': q.query_type,
'difficulty': q.difficulty,
'domain': q.domain
}
for q in self.queries
],
'documents': self.documents,
'chunks': self.chunks
}
with open(filepath, 'w') as f:
json.dump(data, f, indent=2)
@classmethod
def load_from_file(cls, filepath: str):
with open(filepath, 'r') as f:
data = json.load(f)
dataset = cls(data['name'])
dataset.documents = data['documents']
dataset.chunks = data['chunks']
for q_data in data['queries']:
query = EvaluationQuery(
id=q_data['id'],
question=q_data['question'],
reference_answer=q_data.get('reference_answer'),
relevant_chunk_ids=q_data['relevant_chunk_ids'],
query_type=q_data['query_type'],
difficulty=q_data['difficulty'],
domain=q_data['domain']
)
dataset.add_query(query)
return dataset
```
### Dataset Generation
#### Synthetic Query Generation
```python
import random
from typing import List, Dict
class SyntheticQueryGenerator:
def __init__(self):
self.query_templates = {
'factoid': [
"What is {concept}?",
"When did {event} occur?",
"Who developed {technology}?",
"How many {items} are mentioned?",
"What is the value of {metric}?"
],
'analytical': [
"Compare and contrast {concept1} and {concept2}.",
"Analyze the impact of {concept} on {domain}.",
"What are the advantages and disadvantages of {technology}?",
"Explain the relationship between {concept1} and {concept2}.",
"Evaluate the effectiveness of {approach} for {problem}."
],
'comparative': [
"Which is better: {option1} or {option2}?",
"How does {method1} differ from {method2}?",
"Compare the performance of {system1} and {system2}.",
"What are the key differences between {approach1} and {approach2}?"
]
}
def generate_queries_from_chunks(self, chunks: List[Dict], num_queries: int = 100) -> List[EvaluationQuery]:
"""Generate synthetic queries from document chunks"""
queries = []
# Extract entities and concepts from chunks
entities = self._extract_entities_from_chunks(chunks)
for i in range(num_queries):
query_type = random.choice(['factoid', 'analytical', 'comparative'])
template = random.choice(self.query_templates[query_type])
# Fill template with extracted entities
query_text = self._fill_template(template, entities)
# Find relevant chunks for this query
relevant_chunks = self._find_relevant_chunks(query_text, chunks)
query = EvaluationQuery(
id=f"synthetic_{i}",
question=query_text,
reference_answer=None, # Would need generation model
relevant_chunk_ids=[chunk['id'] for chunk in relevant_chunks],
query_type=query_type,
difficulty=random.choice(['easy', 'medium', 'hard']),
domain='synthetic'
)
queries.append(query)
return queries
def _extract_entities_from_chunks(self, chunks: List[Dict]) -> Dict[str, List[str]]:
"""Extract entities, concepts, and relationships from chunks"""
# This would use proper NER in practice
entities = {
'concepts': [],
'technologies': [],
'methods': [],
'metrics': [],
'events': []
}
for chunk in chunks:
content = chunk['content']
# Simplified entity extraction
words = content.split()
entities['concepts'].extend([word for word in words if len(word) > 6])
entities['technologies'].extend([word for word in words if 'technology' in word.lower()])
entities['methods'].extend([word for word in words if 'method' in word.lower()])
entities['metrics'].extend([word for word in words if '%' in word or '$' in word])
# Remove duplicates and limit
for key in entities:
entities[key] = list(set(entities[key]))[:50]
return entities
def _fill_template(self, template: str, entities: Dict[str, List[str]]) -> str:
"""Fill query template with random entities"""
import re
def replace_placeholder(match):
placeholder = match.group(1)
# Map placeholders to entity types
entity_mapping = {
'concept': 'concepts',
'concept1': 'concepts',
'concept2': 'concepts',
'technology': 'technologies',
'method': 'methods',
'method1': 'methods',
'method2': 'methods',
'metric': 'metrics',
'event': 'events',
'items': 'concepts',
'option1': 'concepts',
'option2': 'concepts',
'approach': 'methods',
'problem': 'concepts',
'domain': 'concepts',
'system1': 'concepts',
'system2': 'concepts'
}
entity_type = entity_mapping.get(placeholder, 'concepts')
available_entities = entities.get(entity_type, ['something'])
if available_entities:
return random.choice(available_entities)
else:
return 'something'
return re.sub(r'\{(\w+)\}', replace_placeholder, template)
def _find_relevant_chunks(self, query: str, chunks: List[Dict], k: int = 3) -> List[Dict]:
"""Find chunks most relevant to the query"""
# Simple keyword matching for synthetic generation
query_words = set(query.lower().split())
chunk_scores = []
for chunk in chunks:
chunk_words = set(chunk['content'].lower().split())
overlap = len(query_words & chunk_words)
chunk_scores.append((overlap, chunk))
# Sort by overlap and return top k
chunk_scores.sort(key=lambda x: x[0], reverse=True)
return [chunk for _, chunk in chunk_scores[:k]]
```
## A/B Testing Framework
### Statistical Significance Testing
```python
import numpy as np
from scipy import stats
from typing import List, Dict, Tuple
class ABTestAnalyzer:
def __init__(self):
self.significance_level = 0.05
def compare_metrics(self, control_metrics: List[float],
treatment_metrics: List[float],
metric_name: str) -> Dict:
"""
Compare metrics between control and treatment groups
"""
control_mean = np.mean(control_metrics)
treatment_mean = np.mean(treatment_metrics)
control_std = np.std(control_metrics)
treatment_std = np.std(treatment_metrics)
# Perform t-test
t_statistic, p_value = stats.ttest_ind(control_metrics, treatment_metrics)
# Calculate effect size (Cohen's d)
pooled_std = np.sqrt(((len(control_metrics) - 1) * control_std**2 +
(len(treatment_metrics) - 1) * treatment_std**2) /
(len(control_metrics) + len(treatment_metrics) - 2))
cohens_d = (treatment_mean - control_mean) / pooled_std if pooled_std > 0 else 0
# Determine significance
is_significant = p_value < self.significance_level
return {
'metric_name': metric_name,
'control_mean': control_mean,
'treatment_mean': treatment_mean,
'absolute_difference': treatment_mean - control_mean,
'relative_difference': ((treatment_mean - control_mean) / control_mean * 100) if control_mean != 0 else 0,
'control_std': control_std,
'treatment_std': treatment_std,
't_statistic': t_statistic,
'p_value': p_value,
'is_significant': is_significant,
'effect_size': cohens_d,
'significance_level': self.significance_level
}
def analyze_ab_test_results(self,
control_results: Dict[str, List[float]],
treatment_results: Dict[str, List[float]]) -> Dict:
"""
Analyze A/B test results across multiple metrics
"""
analysis_results = {}
# Ensure both dictionaries have the same keys
all_metrics = set(control_results.keys()) & set(treatment_results.keys())
for metric in all_metrics:
if metric in control_results and metric in treatment_results:
analysis_results[metric] = self.compare_metrics(
control_results[metric],
treatment_results[metric],
metric
)
# Calculate overall summary
significant_improvements = sum(1 for result in analysis_results.values()
if result['is_significant'] and result['relative_difference'] > 0)
significant_degradations = sum(1 for result in analysis_results.values()
if result['is_significant'] and result['relative_difference'] < 0)
analysis_results['summary'] = {
'total_metrics_compared': len(analysis_results),
'significant_improvements': significant_improvements,
'significant_degradations': significant_degradations,
'no_significant_change': len(analysis_results) - significant_improvements - significant_degradations
}
return analysis_results
```
## Automated Evaluation Pipeline
### End-to-End Evaluation
```python
class ChunkingEvaluationPipeline:
def __init__(self, strategies: Dict[str, Any], dataset: EvaluationDataset):
self.strategies = strategies
self.dataset = dataset
self.results = {}
self.profiler = PerformanceProfiler()
self.memory_profiler = MemoryProfiler()
def run_evaluation(self) -> Dict:
"""Run comprehensive evaluation of all strategies"""
evaluation_results = {}
for strategy_name, strategy in self.strategies.items():
print(f"Evaluating strategy: {strategy_name}")
# Reset profilers for each strategy
self.profiler = PerformanceProfiler()
self.memory_profiler = MemoryProfiler()
# Evaluate strategy
strategy_results = self._evaluate_strategy(strategy, strategy_name)
evaluation_results[strategy_name] = strategy_results
# Compare strategies
comparison_results = self._compare_strategies(evaluation_results)
return {
'individual_results': evaluation_results,
'comparison': comparison_results,
'recommendations': self._generate_recommendations(comparison_results)
}
def _evaluate_strategy(self, strategy: Any, strategy_name: str) -> Dict:
"""Evaluate a single chunking strategy"""
results = {
'strategy_name': strategy_name,
'retrieval_metrics': {},
'quality_metrics': {},
'performance_metrics': {}
}
# Track memory usage
self.memory_profiler.take_memory_snapshot(f"{strategy_name}_start")
# Process all documents
self.profiler.start_timer('total_processing')
all_chunks = {}
for doc_id, content in self.dataset.documents.items():
self.profiler.start_timer('chunking')
chunks = strategy.chunk(content)
self.profiler.end_timer('chunking')
all_chunks[doc_id] = chunks
self.memory_profiler.take_memory_snapshot(f"{strategy_name}_after_chunking")
# Generate embeddings for chunks
self.profiler.start_timer('embedding')
chunk_embeddings = self._generate_embeddings(all_chunks)
self.profiler.end_timer('embedding')
self.memory_profiler.take_memory_snapshot(f"{strategy_name}_after_embedding")
# Evaluate retrieval performance
retrieval_results = self._evaluate_retrieval(all_chunks, chunk_embeddings)
results['retrieval_metrics'] = retrieval_results
# Evaluate chunk quality
quality_results = self._evaluate_chunk_quality(all_chunks)
results['quality_metrics'] = quality_results
# Get performance metrics
self.profiler.end_timer('total_processing')
performance_metrics = self.profiler.get_performance_metrics(len(self.dataset.documents))
results['performance_metrics'] = performance_metrics.__dict__
# Get memory metrics
self.memory_profiler.take_memory_snapshot(f"{strategy_name}_end")
results['memory_metrics'] = {
'peak_memory_mb': self.memory_profiler.get_peak_memory_usage(),
'memory_by_operation': self.memory_profiler.get_memory_usage_by_operation()
}
return results
def _evaluate_retrieval(self, all_chunks: Dict, chunk_embeddings: Dict) -> Dict:
"""Evaluate retrieval performance"""
retrieval_metrics = {
'precision': [],
'recall': [],
'f1_score': [],
'mrr': [],
'map': []
}
for query in self.dataset.queries:
# Perform retrieval
self.profiler.start_timer('search')
retrieved_chunks = self._retrieve_chunks(query.question, chunk_embeddings, k=10)
self.profiler.end_timer('search')
# Get relevant chunks for this query
relevant_chunk_ids = set(query.relevant_chunk_ids)
relevant_chunks = [chunk for chunk in retrieved_chunks
if chunk.get('id') in relevant_chunk_ids]
# Calculate metrics
precision = calculate_precision(retrieved_chunks, relevant_chunks)
recall = calculate_recall(retrieved_chunks, relevant_chunks)
f1 = calculate_f1_score(precision, recall)
retrieval_metrics['precision'].append(precision)
retrieval_metrics['recall'].append(recall)
retrieval_metrics['f1_score'].append(f1)
# Calculate averages
return {metric: np.mean(values) for metric, values in retrieval_metrics.items()}
def _evaluate_chunk_quality(self, all_chunks: Dict) -> Dict:
"""Evaluate quality of generated chunks"""
quality_assessor = ChunkQualityAssessor()
quality_scores = []
for doc_id, chunks in all_chunks.items():
# Analyze document
content = self.dataset.documents[doc_id]
analyzer = DocumentAnalyzer()
analysis = analyzer.analyze(content)
# Assess chunk quality
scores = quality_assessor.assess_chunks(chunks, analysis)
quality_scores.append(scores)
# Aggregate quality scores
if quality_scores:
avg_scores = {}
for metric in quality_scores[0].keys():
avg_scores[metric] = np.mean([scores[metric] for scores in quality_scores])
return avg_scores
return {}
def _compare_strategies(self, evaluation_results: Dict) -> Dict:
"""Compare performance across strategies"""
ab_analyzer = ABTestAnalyzer()
comparison = {}
# Compare each metric across strategies
strategy_names = list(evaluation_results.keys())
for i in range(len(strategy_names)):
for j in range(i + 1, len(strategy_names)):
strategy1 = strategy_names[i]
strategy2 = strategy_names[j]
comparison_key = f"{strategy1}_vs_{strategy2}"
comparison[comparison_key] = {}
# Compare retrieval metrics
for metric in ['precision', 'recall', 'f1_score']:
if (metric in evaluation_results[strategy1]['retrieval_metrics'] and
metric in evaluation_results[strategy2]['retrieval_metrics']):
comparison[comparison_key][f"retrieval_{metric}"] = ab_analyzer.compare_metrics(
[evaluation_results[strategy1]['retrieval_metrics'][metric]],
[evaluation_results[strategy2]['retrieval_metrics'][metric]],
f"retrieval_{metric}"
)
return comparison
def _generate_recommendations(self, comparison_results: Dict) -> Dict:
"""Generate recommendations based on evaluation results"""
recommendations = {
'best_overall': None,
'best_for_precision': None,
'best_for_recall': None,
'best_for_performance': None,
'trade_offs': []
}
# This would analyze the comparison results and generate specific recommendations
# Implementation depends on specific use case requirements
return recommendations
def _generate_embeddings(self, all_chunks: Dict) -> Dict:
"""Generate embeddings for all chunks"""
# This would use the actual embedding model
# Placeholder implementation
embeddings = {}
for doc_id, chunks in all_chunks.items():
embeddings[doc_id] = []
for chunk in chunks:
# Generate embedding for chunk content
embedding = np.random.rand(384) # Placeholder
embeddings[doc_id].append({
'chunk': chunk,
'embedding': embedding
})
return embeddings
def _retrieve_chunks(self, query: str, chunk_embeddings: Dict, k: int = 10) -> List[Dict]:
"""Retrieve most relevant chunks for a query"""
# This would use actual similarity search
# Placeholder implementation
all_chunks = []
for doc_embeddings in chunk_embeddings.values():
for chunk_data in doc_embeddings:
all_chunks.append(chunk_data['chunk'])
# Simple random selection as placeholder
selected = random.sample(all_chunks, min(k, len(all_chunks)))
return selected
```
This comprehensive evaluation framework provides the tools needed to thoroughly assess chunking strategies across multiple dimensions: retrieval effectiveness, answer quality, system performance, and statistical significance. The modular design allows for easy extension and customization based on specific requirements and use cases.