Statistical appendix

Abstract

Bleasdale & Nelder (1960) refer to several models which have been used in studying the relationship of yield and density in crop plants and indicate that they regard as most satisfactory the equation: where ω = yield/plant, ρ = number of plants/unit area and A and B are constants. The estimation of the constants for any given case is a very unattractive arithmetic exercise requiring a fairly large number of observations and a tedious iterative calculation; Nelder (1961) has discussed the least squares fit with the equation in the form which may readily be derived from (1) by the substitutions The data in the present case do not justify attempting this process but some progress can be made by the substitutions by means of which it is easy to derive from (1) that