This page contains information about data sources and limitations for SOI's International Boycott Report Study. Please visit International Boycott Report Statistics to access articles and tables from the study. Data for the International Boycott Report Study are based on the population of Forms 5713, International Boycott Report, attached to U.S. income tax returns. Until 2007, the study was based on returns with accounting periods ending in calendar years. Beginning with 2007, the study will be based on tax years. Thus it will include returns with accounting periods ending between July of the study year and June of the subsequent year. Data are subject to taxpayer reporting errors and inconsistencies and processing errors. To minimize such errors, data are subject to validation checks that verify proper relationships among tax return items and consistency with tax law provisions, acceptable reporting practices, and generally accepted accounting principles. Records failing the tests are subjected to further review and correction. In some cases, not all of the data are available from the tax returns as originally filed. Wherever possible, the missing data was imputed, either electronically or manually.