The Partnership Study The Statistics of Income (SOI) Partnership study includes data from Form 1065, US Return of Partnership Income, Form 1065-B, US Return of Income for Electing Large Partnerships, and selected related attachments. Tabulated data by industrial classification, size of assets and size of income are available. This page provides additional information about data produced in SOI's Partnership Study. Please click on a link below to get started. Explanation of Selected Terms Data Sources and Limitations Please visit the Partnership Study Statistics page for data tables and articles.