A method for calculating distances between stimulus response curves (e.g.,
dose response curves) allows classification of stimuli. The response
curves show how the phenotype of one or more cells changes in response to
varying levels of the stimulus. Each "point" on the curve represents
quantitative phenotype or signature for cell(s) at a particular level of
stimulus (e.g., dose of a therapeutic). The signatures are multivariate
phenotypic representations of the cell(s). They include various features
of the cell(s) obtained by image analysis. To facilitate the comparison
of stimuli, distances between points on the response curves are
calculated. First, the response curves may be aligned on a coordinate
representing a separate distance, r, from a common point of negative
control (e.g., the point where no stimulus is applied). Integration on r
may be used to compute the distance between two response curves. The
distance between response curves is used to classify stimuli.
