Methodology and Technical Notes - Confidentiality and Disclosure Limitations

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Confidentiality analyses for the United States were designed to provide reasonable assurance that public-use data files issued by the PISA consortium would not allow identification of individual U.S. schools or students when compared against other public-use data collections. Disclosure limitations included identifying and masking potential disclosure risk to PISA schools and including an additional measure of uncertainty to school and student identification through random swapping of data elements within the student and school file. Swapping was designed to not significantly affect estimates of means and variances for the whole sample or reported subgroups (Krenzke 2006).