Multilingual Health Q&A
Retrieval-first semantic routing for low-resource African health question answering
Zindi Challenge
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Notebook
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Experiment log
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## Overview
This repository documents an end-to-end solution for the **Multilingual Health Question Answering in Low-Resource African Languages** challenge hosted on Zindi in partnership with ITU and the HASH consortium.
Given a health-related question in one of five African languages, the system returns an expert answer **in the same language**. The final approach is a **retrieval-first, per-subset semantic routing pipeline** that indexes curated question–answer pairs and returns verbatim in-corpus answers ranked by dense multilingual similarity, with sparse TF-IDF blending for low-resource subsets.
Development followed a structured workflow:
**EDA → baselines → semantic routing → seven targeted ablations**
All runs are logged in `experiment_log.json` and scored locally with **ROUGE-1** and **ROUGE-L** F1 on `Val.csv`.
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## Results
| Metric | Value |
|---|---|
| **Public score** | 0.572643 |
| **Rank** | 199 |
| **Submissions** | 8 |
| **Primary approach** | Semantic routing with expanded train+validation index (E16) |
| Evaluation mode | Index | Best ROUGE-1 F1 | Experiment |
|---|---|---|---|
| Honest validation (no leakage) | `Train.csv` only | **0.474** | E18 |
| Leaderboard proxy | `Train + Val` | **0.493** | E16b |
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## Approach
```mermaid
flowchart LR
A["Raw CSVs Train / Val / Test"]
B["EDA & Insights"]
C["Preprocessing clean & language map"]
D["Baselines TF-IDF & zero-shot LLM"]
E["Semantic routing per-subset retrieval"]
F["Answer selection verbatim from corpus"]
G["Local evaluation ROUGE on Val"]
H["Export predictions CSV submission"]
A --> B --> C --> D --> E --> F --> G --> H
```
### Design principles
1. **Evidence-driven modelling** — architectural choices trace to quantitative EDA findings.
2. **Baseline anchoring** — sparse and generative baselines define the p …