How to use the dispersion index calculator
Decide whether a species is clumped, random or regular from counts per quadrat using the variance to mean ratio. Enter counts per quadrat in the field above; the variance to mean ratio, dispersion pattern are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “dispersion index”, “clumped or random distribution”, “variance to mean ratio”, “calculate dispersion index”, “find variance to mean ratio”.
Formula
Variables
- n — Counts per quadrat
Worked example
With counts per quadrat = 3,5,2,8,4,6, the calculator gives variance to mean ratio ≈ 1; dispersion pattern ≈ Random distribution text.
Frequently asked questions
What is the dispersion index calculator used for?
Decide whether a species is clumped, random or regular from counts per quadrat using the variance to mean ratio. It helps with questions such as “dispersion index”, “clumped or random distribution”, “variance to mean ratio”.
What is the formula for the dispersion index calculation?
Variance to mean ratio = vari(n) / mean(n). Dispersion pattern (text) = [Variance to mean ratio]<1?"Regular spacing":([Variance to mean ratio]>1.5?"Clumped distribution":"Random distribution"). Here n is counts per quadrat.
What inputs do I need for the dispersion index calculator?
You need counts per quadrat. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the dispersion index calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the dispersion index result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.