Foundations for Evidence-Based Policymaking Act of 2018 This bill requires agency data to be accessible and requires agencies to plan to develop statistical evidence to support policymaking. TITLE I--FEDERAL EVIDENCE-BUILDING ACTIVITIES (Sec. 101) The bill requires agencies to submit annually to the Office of Management and Budget (OMB) and Congress a systematic plan for identifying and addressing policy questions. The plan must include, among other things questions for developing evidence to support policymaking; data the agency intends to collect, use, or acquire to facilitate the use of evidence in policymaking; methods and analytical approaches that may be used to develop evidence to support policymaking; and challenges to developing evidence to support policymaking, including any statutory or other restrictions to accessing relevant data. Each agency shall designate a senior employee as Evaluation Officer to coordinate evidence-building activities and an official with statistical expertise to advise on statistical policy, techniques, and procedures. The OMB shall establish an Advisory Committee on Data for Evidence Building. Agency strategic plans shall contain an assessment of the coverage, quality, methods, effectiveness, and independence of the agency's statistics, evaluation, research, and analysis efforts. The Government Accountability Office (GAO) shall submit to Congress a report that (1) summarizes agency findings and highlights trends in the assessment, and (2) recommends actions to further improve agency capacity to use evaluation techniques and data to support evaluation efforts. The OMB shall issue guidance for program evaluation and identify best practices for evaluation. Agencies must implement such guidance. The Office of Personnel Management shall, for program evaluation within an agency, identify key skills and competencies, establish or update an occupational series, and establish a new career path. TITLE II--OPEN GOVERNMENT DATA ACT Open, Public, Electronic, and Necessary Government Data Act or the OPEN Government Data Act (Sec. 202) This bill requires public government data assets to be published as machine-readable data. The General Services Administration must maintain an online federal data catalogue to provide a single point of entry for the public to access agency data. Each agency shall develop and maintain a comprehensive data inventory and designate a Chief Data Officer. The bill establishes in the OMB a Chief Data Officer Council for establishing government-wide best practices for the use, protection, dissemination, and generation of data and for promoting data sharing agreements among agencies. The GAO shall report to Congress identifying (1) the value of information made available to the public as a result of this bill, (2) whether publishing information that has not yet been published would be valuable to the public, and (3) the completeness of each comprehensive data inventory developed. The OMB shall biennially report on agency performance and compliance with this bill. TITLE III--CONFIDENTIAL INFORMATION PROTECTION AND STATISTICAL EFFICIENCY Confidential Information Protection and Statistical Efficiency Act of 2018 (Sec. 302) The bill codifies and revises the Confidential Information Protection and Statistical Efficiency Act of 2002. Each statistical agency or unit shall (1) produce and disseminate relevant and timely statistical information; (2) conduct credible, accurate, and objective statistical activities; and (3) protect the trust of information providers by ensuring the confidentiality and exclusive statistical use of their responses. (Sec. 303) An agency shall make data assets available to any statistical agency or unit for purposes of developing evidence. This shall not apply to any data asset that is subject to a statute that prohibits the sharing or intended use of such asset. Each statistical agency or unit shall expand access to data assets acquired or accessed to develop evidence while protecting such assets from inappropriate access and use. The OMB shall (1) make public all standards and policies established under this bill; (2) ensure that statistical agencies and units have the ability to make information public on the federal data catalogue; and (3) establish a process through which agencies, the Congressional Budget Office, state, local, and tribal governments, researchers, and other individuals may apply to access the data assets accessed or acquired by a statistical agency or unit for purposes of developing evidence.