addNoise function

Adding noise to perturb data

Various methods for adding noise to perturb continuous scaled variables.

addNoise(obj, variables = NULL, noise = 150, method = "additive", ...)

Arguments

• obj: either a data.frame or a sdcMicroObj-class that should be perturbed
• variables: vector with names of variables that should be perturbed
• noise: amount of noise (in percentages)
• method: choose between additive , correlated , correlated2 , restr , ROMM , outdect
• ...: see possible arguments below

Returns

If obj was of class sdcMicroObj-class the corresponding slots are filled, like manipNumVars, risk and utility.

If obj was of class data.frame or matrix an object of class micro with following entities is returned: - x: the original data

• xm: the modified (perturbed) data

• method: method used for perturbation

• noise: amount of noise

Details

If obj is of class sdcMicroObj-class, all continuous key variables are selected per default. If obj is of class data.frame or matrix , the continuous variables have to be specified.

Method additive adds noise completely at random to each variable depending on its size and standard deviation. correlated and method correlated2 adds noise and preserves the covariances as described in R. Brand (2001) or in the reference given below. Method restr takes the sample size into account when adding noise. Method ROMM is an implementation of the algorithm ROMM (Random Orthogonalized Matrix Masking) (Fienberg, 2004). Method outdect

adds noise only to outliers. The outliers are identified with univariate and robust multivariate procedures based on a robust mahalanobis distances calculated by the MCD estimator.

Examples

data(Tarragona)

a1 <- addNoise(Tarragona)
a1

data(testdata)

# donttest because Examples with CPU time > 2.5 times elapsed time
testdata[, c('expend','income','savings')] <-
addNoise(testdata[,c('expend','income','savings')])$xm

## for objects of class sdcMicroObj:
data(testdata2)
sdc <- createSdcObj(testdata2,
  keyVars=c('urbrur','roof','walls','water','electcon','relat','sex'),
  numVars=c('expend','income','savings'), w='sampling_weight')
sdc <- addNoise(sdc)

References

Domingo-Ferrer, J. and Sebe, F. and Castella, J., On the security of noise addition for privacy in statistical databases , Lecture Notes in Computer Science, vol. 3050, pp. 149-161, 2004. ISSN 0302-9743. Vol. Privacy in Statistical Databases, eds. J. Domingo-Ferrer and V. Torra, Berlin: Springer-Verlag.

Ting, D. Fienberg, S.E. and Trottini, M. ROMM Methodology for Microdata Release Joint UNECE/Eurostat work session on statistical data confidentiality, Geneva, Switzerland, 2005, https://www.unece.org/fileadmin/DAM/stats/documents/ece/ces/ge.46/2005/wp.11.e.pdf

Ting, D., Fienberg, S.E., Trottini, M. Random orthogonal matrix masking methodology for microdata release , International Journal of Information and Computer Security, vol. 2, pp. 86-105, 2008.

Templ, M. and Meindl, B., Robustification of Microdata Masking Methods and the Comparison with Existing Methods, Lecture Notes in Computer Science, Privacy in Statistical Databases, vol. 5262, pp. 177-189, 2008.

Templ, M. New Developments in Statistical Disclosure Control and Imputation: Robust Statistics Applied to Official Statistics, Suedwestdeutscher Verlag fuer Hochschulschriften, 2009, ISBN: 3838108280, 264 pages.

Templ, M. and Meindl, B. and Kowarik, A.: Statistical Disclosure Control for Micro-Data Using the R Package sdcMicro, Journal of Statistical Software, 67 (4), 1--36, 2015. tools:::Rd_expr_doi("10.18637/jss.v067.i04")

Templ, M. Statistical Disclosure Control for Microdata: Methods and Applications in R. Springer International Publishing, 287 pages, 2017. ISBN 978-3-319-50272-4. tools:::Rd_expr_doi("10.1007/978-3-319-50272-4")

See Also

sdcMicroObj-class, summary.micro

Author(s)

Matthias Templ and Bernhard Meindl