Abstract: A computer has a processor and nontransitory memory. The computer receives a list of search keywords to propose to a search engine. For search keywords that are too infrequently used to have historical data to estimate keyword performance, the computer computes linguistic similarity between the sparse-data keyword to other keywords that have sufficient historical keyword performance data to permit a statistically sound estimate for keyword performance. The estimates are submitted to a search engine, and updated by grouping the sparse-data keywords into groups, including at least a high-performing group and a low-performing group, and reallocating budget from the keywords of the low-performing group to keywords of the high-performing group, by reducing estimates for keywords of the low-performing group and increasing estimates of keywords of the high-performing group.