In Stata, how do I detect duplicate observations in a data set?

You can check for duplicate observations in Stata in the following ways:

  • The isid command can detect duplicate observations:
      . isid x1 x2 x3
  • The duplicates command can list and flag duplicate observations. The list subcommand lists the duplicate observations:
      . duplicates list x1 x2 x3
  • The tag subcommand and the generate() option flag duplicate observations by assigning 1 to duplicacy in the variable duple:
      . duplicates tag x1 x2 x3, generate(duple)

If you have questions about using statistical and mathematical software at Indiana University, contact Research Analytics. Research Analytics is located on the IU Bloomington campus at Woodburn Hall 200; staff are available for consultation Monday-Friday 9am-noon and by appointment.

This is document aqea in the Knowledge Base.
Last modified on 2015-06-23 00:00:00.

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