Microaggregation is a set of procedures that distort empirical data in order to guarantee the factual anonymity of the data. At the same time the information content of data sets should not be reduced too much and should still be useful for scientific research. This paper investigates the effect of microaggregation on the estimation of a linear regression by ordinary least squares. It studies, by way of an extensive simulation experiment, the bias of the slope parameter estimator induced by

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... ous microaggregation techniques. Some microaggregation procedures lead to consistent estimates while others imply an asymptotic bias for the estimator. Keywords: microaggregation, disclosure control, simple linear model, bias, consistency 2. Individual ranking (Defays/Anwar 1998): Each variable is microaggregated separately. First, the data set is sorted by the first variable, and the values of this variable are microaggregated. Then, the same procedure is repeated for the second variable and so on. Again, the group size is kept fixed.