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File Formats Explained

Dataset files in the archive are available in file formats that are intended to facilitate user data analysis and ensure preservation. File formats found in Roper Center studies are described below. File formats can also be migrated through the use of tools like StatsTransfer.


Most polls from recent decades and many from earlier periods are available in SPSS portable format. SPSS portable files can be opened by any version of SPSS.


Polls from the most recent years, as well as an increasing number of older studies, are available in Stata 12 file format, and can be easily opened by Stata versions 11 and later.


Many Roper Center datasets from the 20th century are available as ASCII files. ASCII is a widely used  preservation format, and fifty-year-old ASCII files can still easily be read by text editors. However, ASCII files must be converted to modern formats to be utilized by researchers. Roper Center offers guides on converting ASCII to Stata or ASCII to SPSS. Roper Center’s data team is also able to assist researchers with a limited number of conversions. For large numbers of conversions, research service fees apply.

Column binary

The earliest data file format found in the Roper Center collection, column binary was the standard data format for survey research for many years. Column binary files require substantial time and effort to convert to modern format. Roper Center is working diligently to convert all our historical studies out of column binary format. If you require a study to be converted, please email For large numbers of conversions, research service fees apply.


Roper’s new offering, .csv files are popular with users who prefer to conduct analysis in R. These files are also an excellent preservation format and can be read by most statistical packages, as well as spreadsheet programs like Excel.