- Bivariate scatter (plots measurements of any two selected features against each other for many individuals in a single population)
- reduced major axis (RMA) - See Practical booklet, section 3.
No matter how absolute rates of growth may vary, relative rates of growth show remarkably regular relationships, because adaptation of for to function places strict constraints on variantions in shape.
isometry: constant ratio between the two rates at all sizes.
isometric growth conforms to the equation:
y = bx + c D1
True isometric growth is rather exceptional.
The differential realtive of variates is called allometry. Most line of relative growth are thus curved, conforming the allometry equation:
y = bx^a, a = allometric coefficient D2
log y = log b + a log x D3
(waarbij a richtingscoefficient en b kruispunt y-as)