How we calculate impact.

What these numbers are

Every figure on TreeRM is something an organization said about itself, with a link to where it said it. We add a year, a confidence label and, when needed, a note. Then we do arithmetic on those figures. The arithmetic is simple on purpose so anyone can check it.

Trees on record

The larger of two numbers: the organization's latest cumulative total, or the sum of the annual figures we have. Trees planted and trees distributed both count. Seedlings grown in a nursery do not, because many are sold or given to other organizations that then count them.

Annual series

Organization-wide annual figures for trees planted or distributed. When an organization only reports by program, the program figures are added by year. Cumulative figures are never mixed into the series.

Year over year and growth

Year over year is the change between the two most recent consecutive annual figures. Compound annual growth uses the first and last years of the series and needs three or more years. Organizations with under 1,000 trees in the latest year are left out of the growth table because small bases swing wildly.

Trees per volunteer

Trees in a year divided by volunteers engaged in the same year. Where an organization counts volunteer occurrences rather than people, the note says so. This is a description of how the work gets done, not a score.

Dollars per tree

If an organization publishes a cost per tree, we show that. Otherwise we divide total funds raised (US dollars) by trees recorded in the same year and call it what it is: dollars raised per tree recorded. Organizations run education, advocacy and maintenance with the same money, and donations arrive in different years from the planting they pay for. Lowest is not best; it is cheapest per tree recorded.

Survival

Only published survival rates are shown, with the year and confidence. A sampled field study counts as independently verified; an organization's own monitoring counts as self-reported.

Transparency score

A 0 to 100 score for how much an organization lets the public check. It measures reporting, not outcomes. Points: annual tree figures, 5 per year up to 20; latest figure within two years, 15 (within four years, 7); every figure sourced, 10; financials or cost per tree published, 15; survival or monitoring reported, 15; at least one independently verified figure, 10; figures broken out by program, 10 (programs named without figures, 4); volunteers reported or public events listed, 5.

Labels: 80 and up, open book; 60 to 79, well documented; 40 to 59, partly documented; 20 to 39, thin; under 20, opaque.

Confidence labels

Self-reported: the organization's own published number. Independently verified: a third party checked it. Estimated: we derived it and the note says how.

When this changes

The formulas live in one file in the site's code and this page is written from it. If the method changes, this page changes with it and the date below moves.