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Review of the United States Marshals Service's Prisoner Tracking System

Report No. 04-29
August 2004
Office of the Inspector General

Appendix 7
General Accounting Office
Assessing the Reliability of Computer-Processed Data

Data Integrity Assessment Guidelines

Data reliability refers to the accuracy and completeness of computer-processed data, given the intended purposes for use. Computer-processed data include data (1) entered into a computer system and (2) resulting from computer processing. Computer-processed data can vary in form - from electronic files to tables in published reports. The definition of computer-processed data is therefore broad. In this guidance, the term data always refers to computer-processed data.

The "Yellow Book" requires that a data reliability assessment be performed for all data used as support for engagement findings, conclusions, or recommendations.19 This guidance will help you to design a data reliability assessment appropriate for the purposes of the engagement and then to evaluate the results of the assessment.

Data are reliable when they are (1) complete (they contain all of the data elements and records needed for the engagement) and (2) accurate (they reflect the data entered at the source or, if available, in the source documents).20,21 A subcategory of accuracy is consistency. Consistency refers to the need to obtain and use data that are clear and well-defined enough to yield similar results in similar analyses. For example, if data are entered at multiple sites, inconsistent interpretation of data rules can lead to data that, taken as a whole, are unreliable. Reliability also means that for any computer processing of the data elements used, the results are reasonably complete and accurate, meet your intended purposes, and are not subject to inappropriate alteration.

  1. The GAO's "Government Auditing Standards," 2003 Revision, commonly referred to as the "Yellow Book" sets forth generally accepted government auditing standards for use by government auditors.
  2. A data element is a unit of information with definable parameters (for example, a social security number), sometimes referred to as a data variable or data field.
  3. Source document. Information that is the basis for entry of data into a computer.