Technology for selecting promotion(s) to display in a page of an application for display to a user is described. An example method includes determining a promotion for a product; calculating for the promotion a posterior distribution of a user-action probability reflecting estimates for a user response to a display of the promotion for the product on a computing device of the user; determining the posterior distribution as collapsing beyond a certain threshold; responsive thereto, calculating an uncollapsed posterior distribution of the user-action probability reflecting modified estimates for the user response to the display of the promotion for the product on a computing device of the user; storing the uncollapsed posterior distribution of the user-action probability in a response database; and determining whether to select the promotion from the promotion database for display on a computing device of the user based on the modified estimates.