Computer-implemented method and computer program product

A computer-implemented method for determining a crowdsourced association between a first user identifier and a second user identifier, the second user identifier comprising an identifier for a user of a service accessible over a network, the method comprising:

• (i) responsive to an event identifying the first user identifier, performing a search of data associated with users of the service to identify one or more users of the service having a potential association with the first user identifier, each of the one or more identified users of the service having a respective second user identifier;
• (ii) inviting one of a plurality of users of the service to select one of the one or more identified users from (i) in relation to the first user identifier;
• (iii) responsive to a selection by the said user at (ii), determining a tier of linkage, from at least two defined tiers of linkage, between the said user and the one of the one or more identified users selected by the said user at (ii);
• (iv) recording a vote, of the tier of linkage determined at (iii), in respect of the one of the one or more identified users selected at (ii) in relation to the first user identifier;
• (v) repeating (ii) to (iv) in respect of different ones of the plurality of users of the service;
• (vi) assigning a respective threshold to the votes recorded at (iv) according to the tier of linkage of the votes;
• and
• (vii) responsive to a number of the votes recorded at (iv) of at least one of the at least two defined tiers of linkage achieving the respective assigned threshold, determining whether the association between the first user identifier and the respective second user identifier is a crowdsourced association.