1. A diagnostic apparatus for use in relation to an industrial process, the apparatus comprising a data processing apparatus programmed to: receive object data for a set of physical product units that have been subjected nominally to the same industrial process, the object data for each product unit representing one or more parameters measured on the product unit at points spatially distributed across the product unit; define a multidimensional space in which the object data for each of the product units can be represented as a vector; perform a multivariate analysis on the object data to obtain one or more component vectors in the multidimensional space; extract diagnostic information about the industrial process at least partly using certain one or more product units identified out of the set of product units based on the position of the respective vector of the identified one or more product units when projected onto one or more of the component vectors; and based on the diagnostic information, output electronic data for configuration or modification of the industrial process or of a measurement process of product units subjected to the industrial process.