Preventing contrast effect exploitation in item recommendations

A system comprising:

• a request module configured to receive a set of recommendable items and a request to select, from the set of recommendable items, a group of items;
• a biased conversion rate prediction module configured to determine, for each item of the set of recommendable items, biased conversion rates of the item when included within each possible contrast group of a set of possible contrast groups that include the item;
• an unbiased conversion rate prediction module configured to determine, for each item of the set of recommendable items based on the respective determined biased conversion rates, an unbiased conversion rate for the item;
• an item selection module configured to select a recommended item comprising an item of the set of recommendable items having a greatest unbiased conversion rate;
• and
• a contrast group selection module configured to select, for the recommended item, a contrast group comprising the recommended item from among a plurality of contrast groups that include the recommended item, wherein the selected contrast group provides a greatest biased conversion rate for the recommended item of the plurality of contrast groups.

A non-transitory computer-readable medium having program code that is stored thereon, the program code executable by one or more processing devices for performing operations comprising:

• accessing a set of recommendable items;
• a contrast group from the set of recommendable items by applying a recommendation model to the set of recommendable items, wherein the recommendation model comprises:
• an item selection model configured to:
• determine, for each item of the set of recommendable items, an unbiased conversion rate;
• select a recommended item comprising an item of the set of recommendable items having a greatest unbiased conversion rate;
• a contrast group selection model configured to select, for the recommended item, a contrast group comprising the recommended item;
• and
• transmitting, responsive to the request, the contrast group.