How SAMI works
SAMI is a sentiment index for the South African mining sector. Every score on this site is computed from public news articles, not set by hand. This page explains how raw articles become the heatmap, entity scores, and commodity pulse you see on the dashboard.
1. The atomic unit: an article fact
The pipeline ingests one record per article. Each record carries the article's metadata (title, source, publication date, URL, and the mining location it concerns) plus a set of annotations. An annotation is a single observation: a sentiment score in the range −1.0 to +1.0 for one entity along one dimension.
This cycle compiled 91 articles across 25 entities from 4 sources.
2. Dimensions
Sentiment is tracked separately along 5 dimensions, so a company can be viewed positively on one axis and negatively on another:
- Production
- Policy
- ESG
- Labor
- Price
An entity's Overall score is the weighted mean of all its annotations across every dimension.
3. Weighting
Not every article counts equally. Each annotation is weighted by two factors when aggregated:
- Source authority — more established outlets carry more weight (see Source List).
- Recency — older coverage decays exponentially, with a half-life of 30 days. An article 30 days old counts half as much as one published today.
A cell's score is the weight-adjusted mean of every matching annotation. Cells marked — have no coverage this cycle.
4. Scoring scale
Scores map to colour tiers on the heatmap:
| Range | Tier | Reading |
|---|---|---|
| +0.5 to +1.0 | strong | Strongly positive |
| +0.3 to +0.5 | pos | Positive |
| +0.1 to +0.3 | slight | Slightly positive |
| −0.1 to +0.1 | neutral | Neutral / mixed |
| −0.3 to −0.1 | slight | Slightly negative |
| −0.5 to −0.3 | neg | Negative |
| −1.0 to −0.5 | strong | Strongly negative |
5. Contested entities
An entity is flagged contested when its coverage contains both clearly positive and clearly negative articles in the same cycle — a sign of genuine disagreement rather than consensus. 6 entities are contested this cycle.
Pilot snapshot, last compiled 9 Jun 2026. SAMI is an experimental research tool, not financial advice. Sentiment is a measure of news tone, not a forecast of price or performance.