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The toenail data come from a Multicenter study comparing two oral treatments for toenail infection. Patients were evaluated for the degree of separation of the nail. Patients were randomized into two treatments and were followed over seven visits - four in the first year and yearly thereafter. The patients have not been treated prior to the first visit so this should be regarded as the baseline.


A data frame with 1908 observations on the following 5 variables:


a numeric vector giving the ID of patient


a numeric vector giving the response (0=none or mild seperation, 1=moderate or severe)


a numeric vector giving the treatment group


a numeric vector giving the time of the visit (not exactly monthly intervals hence not round numbers)


a numeric vector giving the number of the visit


De Backer, M., De Vroey, C., Lesaffre, E., Scheys, I., and De Keyser, P. (1998). Twelve weeks of continuous oral therapy for toenail onychomycosis caused by dermatophytes: A double-blind comparative trial of terbinafine 250 mg/day versus itraconazole 200 mg/day. Journal of the American Academy of Dermatology, 38, 57-63.


This dataset was copied from the DPpackage, which is scheduled to be discontinued from CRAN in August 2019.


Lesaffre, E. and Spiessens, B. (2001). On the effect of the number of quadrature points in a logistic random-effects model: An example. Journal of the Royal Statistical Society, Series C, 50, 325-335.

G. Fitzmaurice, N. Laird and J. Ware (2004) Applied Longitudinal Analysis, Wiley and Sons, New York, USA.

Van Buuren, S. (2018). Flexible Imputation of Missing Data. Second Edition. Chapman & Hall/CRC. Boca Raton, FL.

See also