A data retrieval control method, the method comprising: receiving a request; generating a request-based variable using data associated with the request, wherein the data is input to a request-based variable generation model to generate the request-based variable; in response to determining that using further data as further input to the request-based variable generation model may alter the request-based variable, determining whether or not to retrieve the further data based on a comparison involving a data retrieval loss indicator and a data non-retrieval loss indicator, the data retrieval loss indicator being indicative of a loss associated with retrieving the further data and the data non-retrieval loss indicator being indicative of a loss associated with not retrieving the further data; and making a decision associated with the request based on a determinative request-based variable, wherein, when the comparison indicates that the data retrieval loss outweighs the data non-retrieval loss: the determination is not to retrieve the further data; and the request-based variable is used as the determinative request-based variable, and wherein, when the comparison indicates that the data non-retrieval loss outweighs the data retrieval loss: the determination is to retrieve the further data; the further data is retrieved; the request-based variable is regenerated using the request data and the further data as inputs to the request-based variable generation model to generate a regenerated request-based variable; and the regenerated request-based variable is used as the determinative request-based variable. receiving a request; generating a request-based variable using data associated with the request, wherein the data is input to a request-based variable generation model to generate the request-based variable; in response to determining that using further data as further input to the request-based variable generation model may alter the request-based variable, determining whether or not to retrieve the further data based on a comparison involving a data retrieval loss indicator and a data non-retrieval loss indicator, the data retrieval loss indicator being indicative of a loss associated with retrieving the further data and the data non-retrieval loss indicator being indicative of a loss associated with not retrieving the further data; and making a decision associated with the request based on a determinative request-based variable, wherein, when the comparison indicates that the data retrieval loss outweighs the data non-retrieval loss: the determination is not to retrieve the further data; and the request-based variable is used as the determinative request-based variable, and the determination is not to retrieve the further data; and the request-based variable is used as the determinative request-based variable, and wherein, when the comparison indicates that the data non-retrieval loss outweighs the data retrieval loss: the determination is to retrieve the further data; the further data is retrieved; the request-based variable is regenerated using the request data and the further data as inputs to the request-based variable generation model to generate a regenerated request-based variable; and the regenerated request-based variable is used as the determinative request-based variable. the determination is to retrieve the further data; the further data is retrieved; the request-based variable is regenerated using the request data and the further data as inputs to the request-based variable generation model to generate a regenerated request-based variable; and the regenerated request-based variable is used as the determinative request-based variable.