Novice seeks hint for plant nursery stat. problem

[Chris Barr]

I'm seeking pointers to solve this (hopefully) simple problem, e.g.
relevant algorithm or example in a book.

A plant nursery friend has 140 acres of azaleas. He's tracked
15 or 20 factors related to their growth. Some grow much
better than others and he's trying to understand why. In some
cases it's easy to see, in others the differences are confusing,
He'd like to understand the cases where "this shouldn't happen."

Variables include:
variety of azalea, degree of brackish water (this is near
a salt water bay), sunlight, depth of topsoil, humus/sand/clay
ratios in topsoil, acidity, nutrient levels & ratios, neighboring
vegetation, spacing of plants, frequency of re-planting, type
of fertilizer, rainfall, sprinkler coverage, insect infestation,
mulch type, slope, elevation, when plowed, etc.

He's tracked all this on paper for 10 years or more, and scratches
his head because it ought to be easy to nail down why some thrive
well in conditions in which others grow slowly.

I notice some can be ranked on a scale, e.g. hours of sun, and
others cannot, e.g. species type.

I'm an experienced C programmer (Borland), sometime database
programmer (Oracle, Approach) and spreadsheet user.

Thanks, in advance,

- Chris Barr
cb...@s35.cv.com