The Commissioner shall provide, directly or through grants or contracts, for the evaluation of projects assisted under this subchapter including evaluations that describe and measure the impact of such projects, their effectiveness in achieving stated goals, their impact on related programs, and their structure and mechanisms for delivery of services, including, where appropriate, comparisons with appropriate control groups composed of persons who have not participated in such projects. Evaluations shall be conducted by persons not directly involved in the administration of the program or project evaluated.