The axioms on preference define the set of all actual or potential consumers or, equivalently, the set of all utility functions representing preferences. A single consumer, a group of consumers, and the consuming sector are treated as samples chosen from either of these sets. A linear consumption technology is introduced, and the cross effects are shown to defend on the interaction of the technology with the properties of preference expressed by the Antonelli matrix. Some weak probabilistic assumptions about the properties of the Antonelli matrix yield expected values and variances for all cross effects. When the technology matrix is an identity matrix, as is true for conventional consumer theory, all pairs of market goods are predicted to be weak substitutes for each other, and the expected signs are significant for a sufficiently large sample of consumers. A wide range of statistically significant cross effects is obtained when the technology requires joint use of market goods in consumption activities, but the classification of market goods as complements or substitutes depends almost entirely on the technology.