The sight-sized method of measurement is based on the premise that the drawing of the figure will be the same size as the figure appears to the person drawing. The further away you stand from the model, the smaller the figure in your drawing. This method is linked to the traditions of one point perspective and is currently promoted by private 'atelier' schools.
The traditional positioning of the model and artist, evidenced in initial sight sized drawings, is disrupted when the figure is drawn life sized or larger. The paper is then positioned next to the model and the artist has to stand back, at a marked position, look at the model and the paper and move forward to make the drawing.
In this drawing method there is no barrier between the model and artist, and the act of looking is not masked. In sight- sized drawings the relationship between the model and the drawing is directly translated into the scale of the work produced. It is tangible evidence for the physical proximity of artist and model.
With thanks to Anastasia Wilding for information on the sight-sized methodology.