first-order interaction
an effect in which the pattern of values on one variable changes depending on the combination of values on two other variables. For example, an analysis could reveal that although gender and teaching style may each have some effect on performance, the specific degree or amount of the performance effect changes depending on the particular combination of gender and teaching method. Thus, male students may show moderately high performance regardless of teaching style, whereas female students may show high performance with a hands-on teaching style and low to moderate performance with a lecture teaching style. See also higher order interaction.