Score = weighted average of (4 - exposure) over the dimensions that have data, shown as 0-100. You set the weights; by default all are equal. A decision aid only.
Data and trust
How it is computed, with nothing hidden:
For each place and dimension, suitability = 4 - exposure score (so 4 = best, 0 = worst).
Score = sum(weight x suitability) / sum(weight x 4) x 100.
Dimensions without data for a place are left out for that place and listed; compare coverage before trusting a close ranking.
Weights go from 0 (ignore) to 5 (very important). They are saved in this browser only.
It leaves out everything that is not in this data: cost of living, visas, healthcare, language, family, politics. The official advisories are shown next to it for that reason.
Why it matters for Koh Samui
Different people weigh the same facts differently. The sliders make that explicit instead of hiding it in a single number.
Example
If cold matters three times more than heat to you, set Cold to 3 and Heat stress to 1: the ranking changes instantly.