A method of obtaining parametric test data for use in monitoring alignment between layers of a semiconductor device. The method employs a test structure comprising a meander (10, 30) of the material of a first layer of the semiconductor device, deposited relative to a conductive line (18,38). A number of sets (16a, 16b, 16e, 16d) of components 16, such as contacts or vias, are provided relative to the meander (10), at successively smaller distances therefrom. A single analogue measurement can be performed between a first and (A) of the meander (10, 30) and the conductive line (18, 38) so as to determine the resistance therebetween, and the critical distance at (or on acceptable margin in relation thereto) between the first layer and a component of the semiconductor device can be obtained.