of the BAO angular scale is the production of a set of random catalogues with the same features as the observed quasar catalogue, apart from clustering ones: they should contain cosmic objects homogeneously distributed in the same geometry of the survey, and their number should be equal to the number of objects in the data catalogue.

The methodology used to generate our random catalogues in order to obtain a homogeneous Poisson sampling of cosmic objects [@Peebles-Hauser] was to shuffle the data angular coordinates in the shell in a way that any possible correlation will be destroyed [@Rego]. There are many approaches to produce these simulated data, but perhaps the most important task is to certify that they are indeed featureless, and the simplest way to do this is through a [*null test*]{} (see, e.g., section 5 in ref. [@Landy-Szalay]). Consider that we have produced $N+1$ random catalogues. A null test assumes any of the random catalogues as the [*pseudo-data catalogue*]{} and estimates the 2PACF, using equation (\[2PACF\]), with the remaining $N$ random catalogues. Since there is no preferred clustering at any scale, the expected 2PACF is, up to the error bars, a null correlation, that is, one does not expect 