The invention provides methods for removing unwanted response components (i.e., "artifacts") from a measured biological profile comprising measurements of a plurality of cellular constituents of a cell or organism in response to a perturbation. The methods involve subtracting from the measured biological profile one or more artifact patterns, each of which comprises measurements of changes in cellular constituents as a result of deviation of one or more experimental variables, such as cell culture density and temperature, hybridization temperature, as well as concentrations of total RNA and/or hybridization reagents, from desired values.