Abstract: A system and method for measuring or at least detecting the effect of at least implicit communication on transactions within a social group, optionally such as consumer purchases for example. The group may optionally comprise a social network, a pair, 3 or more individuals and so forth. By “implicit communication” it is meant communication for which there is no record, for example in a database. The aftereffects of such communication may optionally be determined, detected and/or measured through detection and/or measurement of influence, as described in greater detail below. For example, if a first consumer performs purchase of an item and a second consumer later purchases the same or similar item within a given time period, the two purchases may optionally be linked through influence which may in turn have optionally occurred through implicit communication.