Handle missing covariates in Xpose GAM

Hi, Does anyone know how to handle missing covariates using GAM function of Xpose (xpose.gam)? Interestingly, “-99” (the default value of Xpose for missing data) is correclty recognized as missing value when the covariates summary is created, conversely xpose.gam considers it as a number, producing undesired results. Is there a way to pass an option like na=na.gam.replace or na=na.omit from xpose.gam to gam or should I replace NA's "manually" before calling xpose.gam? Many thanks for your help Kind Regards Marco ------------------------------------------------------------------------------ Marco Campioni, PhD Modelling & Simulation Senior Scientist Exploratory Medicine Merck Serono S.A. - Geneva 9, Chemin des Mines 1202 Geneva, Switzerland Location: B1.4 Phone: +41 22 414 4554 Fax: +41 22 414 3059 Email: [email protected] This message and any attachment are confidential and may be privileged or otherwise protected from disclosure. If you are not the intended recipient, you must not copy this message or attachment or disclose the contents to any other person. If you have received this transmission in error, please notify the sender immediately and delete the message and any attachment from your system. Merck KGaA, Darmstadt, Germany and any of its subsidiaries do not accept liability for any omissions or errors in this message which may arise as a result of E-Mail-transmission or for damages resulting from any unauthorized changes of the content of this message and any attachment thereto. Merck KGaA, Darmstadt, Germany and any of its subsidiaries do not guarantee that this message is free of viruses and does not accept liability for any damages caused by any virus transmitted therewith. Click http://disclaimer.merck.de to access the German, French, Spanish and Portuguese versions of this disclaimer.