The golden ratio (occasionally called the golden section or the golden mean) has attracted interest from people over the years. Scientists in a wide range of fields have explored or questioned possible presence of golden-ratio proportions. Examples are to be found in nature itself as well as in man-made creations (pieces of art, architecture). If possible, having a sample of observations at hand, a statistical test might be useful for judgment. Some popular beliefs, not to say myths, about the golden ratio can be regarded as misconceptions: statistical tests might be useful for judgment. In this paper we use a regression technique to investigate a problem from musicology: whether the golden-ratio proportion could be said to be present in piano sonatas by W.A. Mozart. The model allows for comparison with works by another master composer, J. Haydn.