Gaussian processes are powerful regression models specified by parameterize
d mean and covariance functions. Standard approaches to choose these parame
ters (known by the name hyperparameters) are maximum likelihood and maximum
a posteriori. In this article, we propose and investigate predictive appro
aches based on Geisser's predictive sample reuse (PSR) methodology and the
related Stone's cross-validation ICV) methodology. More specifically, we de
rive results for Geisser's surrogate predictive probability (GPP), Geisser'
s predictive mean square error (GPE), and the standard CV error and make a
comparative study. Within an approximation we arrive at the generalized cro
ss-validation (GCV) and establish its relationship with the GPP and GPE app
roaches. These approaches are tested on a number of problems. Experimental
results show that these approaches are strongly competitive with the existi
ng approaches.