IndexFair › Methodology › Source weighting
Each source contributes to a score by a fixed trust weight. The spread of that evidence becomes the ± interval and the confidence label — the score is a point, the interval is the honesty around it.
Trust weights are fixed per source tier and applied before aggregation — they do not change with a brand's score, cannot be overridden per brand, and are published configuration. A wider confidence interval means less agreement across sources or fewer effective sources, not a worse brand.
What ± means. 7.2 ±1.3 says the index very likely sits in 5.9–8.5. A wider interval means less agreement or less evidence — never a worse brand. Affects: the ± and confidence chip on every score.
All figures are illustrative. The interval of ±1.3 reflects the spread across the three sources — not a failing grade.