Fighting the floating correlations: Expectations and complications in extracting statistical correlations from the string theory landscape

The realization that string theory gives rise to a huge landscape of vacuum solutions has recently prompted a statistical approach towards extracting phenomenological predictions from string theory. Unfortunately, for most classes of string models, direct enumeration of all solutions is not computationally feasible and thus statistical studies must resort to other methods in order to extract meaningful information. In this paper, we discuss some of the issues that arise when attempting to extract statistical correlations from a large data set to which our computational access is necessarily limited. Our main focus is the problem of "floating correlations." As we discuss, this problem is endemic to investigations of this type and reflects the fact that not all physically distinct string models are equally likely to be sampled in any random search through the landscape, thereby causing statistical correlations to float as a function of sample size. We propose several possible methods that can be used to overcome this problem, and we show through explicit examples that these methods lead to correlations and statistical distributions which are not only stable as a function of sample size, but which differ significantly from those which would have been naïvely apparent from only a partial data set.