Calculation of an index of diversity (d) from the formula: d = N(N-1) / Σn(n-1), where N = total number of organisms of all species and n = total number of organisms of each species
The index of diversity is a number you calculate from a formula. It tells you how evenly individuals are spread across different species in a community.
Formula
d = N(N−1) / Σn(n−1)
Real World
Ecology students sampling a school playing field might count 80 organisms across 5 species; plugging N = 80 and each species' n into the formula lets them compare diversity before and after a wildflower planting scheme.
Exam Focus
Show every Σn(n−1) row in a table — examiners award method marks for each correct species calculation, not just the final answer.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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