Modelling the effects of the survey window function. The effects of the simplified geometry of the survey only, i.e. the parent sample (filled blue circles) and of the full angular mask (filled red circles) are compared. The dashed and dotted lines show how well these effects are modelled by convolving the input P(k) (solid line) with our model for the window functions of the two cases. The relative accuracy in the case of the full window function (geometry plus mask) is explicitly shown in the bottom panel. The insets show a blow-up of the Baryonic Acoustic Oscillations, obtained by dividing the input spectrum by a “no-wiggles" one (solid line). This is compared to the actual signal expected when P(k) is convolved with the VIPERS window function (dashed line).