Statistical properties of the horizontal to vertical spectral ratios (hvsr) applied to noise recording are analyzed in order to define optimal strategies for numerical processing and identification of possible artifacts. To this purpose, two time series have been analyzed: one constituted by environmental seismic noise in the presence of a genuine physical signal and one relative to pure instrumental noise, both obtained with the same experimental apparatus. By means of suitable statistics, some guidelines for the hvsr analysis are provided. A statistical test proposed by Albarello (2001) for the identification of artifacts in the hvsr function has been analyzed and invalidated.