This work describes a novel application of a recently developed statis
tical partial least-squares regression technique for the problem of es
tablishing relationships between experimental variables in crystalliza
tion trials and the experimental results. To validate this method publ
ished sets of factorially designed crystallization trials were analyze
d and it was discovered that these derived models show very good predi
ctivity. These mathematical constructs cannot explain the detailed mec
hanism of crystallization, but are a pragmatic and powerful tool which
enables the crystal growers to set up crystallization trials not only
in a rational manner but also with confidence. This is a useful and a
general methodological approach particularly when crystallizing prote
ins of limited supply.