Evidence-Based Policymaking Commission Act of 2014 - Establishes in the executive branch a Commission on Evidence-Based Policymaking. Directs the Commission to conduct a comprehensive study of the data inventory, data infrastructure, and statistical protocols related to federal policymaking and the statistical and programmatic agencies responsible for maintaining that data to:

• determine the optimal arrangement for which administrative data on federal programs and tax expenditures and related data series may be integrated and made available to facilitate program evaluation, policy-relevant research, and cost-benefit analyses by qualified researchers and institutions;
• make recommendations on how data infrastructure and protocols should be modified to best fulfill those objectives; and
• make recommendations on how best to incorporate outcomes measurement, institutionalize randomized controlled trials, and rigorous impact analysis into program design.

Requires the Commission to consider if and how to create a clearinghouse for program and survey data.

Terminates the Commission not later than 18 months after enactment of this Act.