Although it may be more difficult to get an accurate drawing, this method is much more flexible than the Sight-Size method. The choice of which of the two methods to use should be made dependent on the motif and the situation.
When drawing a self-constructed still life in your own studio, the Sight-Size method would probably be the better choice, while you would prefer the Comparative method when you draw in your sketchbook.
When drawing with the comparative drawing method, the artist has to orient himself in already drawn proportions in his drawing. If you, for example, are drawing a human being it can compare the size of the head with other parts of the model. It is important in this method to always measure from the same position and make as many measurements as possible.
Measuring and comparing means gathering information about the subject and more information lead to a more accurate drawing.
Just as with the Sight-Size method, the artist also has other ways to achieve a correct drawing in the comparative method.
1. Landmarks/points to refer to
Are there important points in the motif, which the artist can orient himself to? When drawing a model, this could be, for example, the larynx, the outer points of the clavicle, or the height of the navel.
The artist can look for certain angles on the motif and compare them with those in his drawing.
3. Horizontal / Vertical overlaps
Are certain points of the subject on a horizontal or vertical line?
Just as with the Sight-Size method, it may be useful to first mark the outermost points of its motif. This makes it possible to ensure that the drawing does not suddenly become too big for the paper or the entire composition moves.
Overall, one can say that both the Sight-Size and the Comparative Method have their right to exist. Both are only tools for the artist to create his works, and the more tools the artist possesses, the more flexible and successful it is.