This article examines a method of adjusting subgroup means when there are errors both in the allocation of elements to the subgroups and in the measurement of the response. The advantages with the method are that it is simple, it is also applicable when there are many subgroups, and it requires no distributional assumptions for the response variable. The method is compared to the maximum likelihood method for a dichotomous response, and an example from the Swedish Level of Living Survey is given.