PSIA is an approach developed in 2001 by the World Bank and other donors, while the PIA came about in 2006 as a result of discussions within the OECD Development Assistance Committee (DAC). The main difference between both tools is that the PIA is designed to focus on project, programmes or specific policy reforms, while the PSIA approach is better for macroeconomic and structural policy reforms.
The International Poverty Centre (IPC) has recently released the last number of its journal Poverty in Focus. This issue focuses on Poverty and Social Impact Analysis (PSIA) and Poverty Impact Assessment (PIA), a field in which the IPC is currently administering a joint UNDP-World Bank Project.
Since PSIA was introduced, approximately 150 assessments have been conducted and the IPC show that it has been applied with a different degree of success in different occasions. Most of the articles in the journal agree that further progress needs to be made in order to unleash PSIA’s full potential.
(Source: EURODAD) http://www.undp-povertycentre.org/pub/IPCPovertyInFocus14.pdf