TITLE: Cross-Validation with LULOO AUTHORS: Paul Haase S{\o}rensen & Magnus N{\o}rg{\aa}rd Department of Automation, B326 Technical University of Denmark DK-2800 Lyngby, Denmark Phones: (+45) 45253581, (+45) 45253565 Fax: (+45) 45881295 Emails: phs,pmn@iau.dtu.dk Lars Kai Hansen & Jan Larsen Department of Mathematical Modelling B349 Technical University of Denmark DK-2800 Lyngby, Denmark Phones: (+45) 45253889, (+45) 45253923 Fax: (+45) 45880117 Emails: lkhansen@ei.dtu.dk jl@imm.dtu.dk The leave-one-out cross-validation scheme for generalization assessment of neural network models is computationally expensive due to replicated training sessions. Linear unlearning of examples has recently been suggested as an approach to approximative cross-validation. Here we briefly review the linear unlearning scheme, dubbed LULOO, and we illustrate it on a system identification example. Further, we address the possibility of extracting confidence information (error bars) from the LULOO ensemble. Accepted for 1996 International Conference on Neural Information Processing, ICONIP'96, Hong Kong, Sept. 24-27, 1996.