The Data Documentation Initiative (DDI) is an open, international effort to provide a a standard way of describing data from the social, behavioral and economic sciences.  DDI Schemas are in XML and can describe metadata across the life-cycle from questionnaire design through analysis.  See www.dddalliance.org.

Stat/Transfer supports DDI 3.1 Standard.  The data are contained in two files: the dictionary information is stored in a file with the extension .xml and the data are stored in a separate  delimited ASCII file with the extension .dat. 

Standard extension:  xml, dat

Reading DDI

Stat/Transfer will read and use DDI variable and value labels. Delimited data files are supported for reading and writing.  The missing values and the delimiter are taken from the Schema.

Writing DDI

Stat/Transfer writes delimited DDI.  The specification requires that elements within the Schema be identified by an "agency".  This is typically a url.  By default it is "example.org", but you should change it to something more appropriate at Output Options(1) of the Options dialog box.

Missing Values

On input the missing value is taken from the Schema.  On output it is a blank.

Output Variable Types

The output variable type that results from each target variable type is given in the following table: