Multivariate autoregressive model in the study of interrelations between cardiorespiratory signals in neonatal lambs : J. Grönlund, S. Kallib, H. Ihalainenc, A. Siimesa, K. Antilaa and I. Välimäkia. aCardiorespiratory Research Unit, University of Turku, bMedical Engineering Laboratory, Technical Research Centre of Finland and cMeasurement Engineering Laboratory, Tampere University of Technology, Finland