Abstract: A method of testing a product using confidence estimates is provided. The method includes identifying a set of candidate tests and estimating a respective confidence score for each candidate test, the confidence scores reflecting a level of confidence that the corresponding candidate tests will pass or fail when being performed on the product, the estimating including determining the respective confidence scores in dependence upon at least one of (i) previously obtained test results, (ii) changes to the product since a previous estimation or regression test has been performed and (iii) information regarding a user. The method includes identifying a candidate test having a confidence score that is below a threshold, in response to the identification of the candidate test, performing the candidate test, and providing, to a user, results of the performing of the candidate test.