The basic sciences all require an ability to measure the amounts of substances under study. With new methods of measurement constantly being proposed there is a need for techniques for comparing these methods in terms of their precision and accuracy. Of particular interest is the case in which none of the individual methods are known to measure “truth”. A multiple methods comparison technique for this case is proposed in this paper, and is illustrated by an example from the field of clinical chemistry. Estimates of the components of variance for each method are developed, and some of their properties explored.