Menzerath's law, the tendency of Z (the mean size of the parts) to decrease as X 
(the number of parts) increases, is found in language, music and genomes. 
Recently, it has been argued that the presence of the law in genomes is an 
inevitable consequence of the fact that Z=Y/X, which would imply that Z scales 
with X as Z ∼ 1/X. That scaling is a very particular case of Menzerath-Altmann 
law that has been rejected by means of a correlation test between X and Y in 
genomes, being X the number of chromosomes of a species, Y its genome size in 
bases and Z the mean chromosome size. Here we review the statistical foundations 
of that test and consider three non-parametric tests based upon different 
correlation metrics and one parametric test to evaluate if Z ∼ 1/X in genomes. 
The most powerful test is a new non-parametric one based upon the correlation 
ratio, which is able to reject Z ∼ 1/X in nine out of 11 taxonomic groups and 
detect a borderline group. Rather than a fact, Z ∼ 1/X is a baseline that real 
genomes do not meet. The view of Menzerath-Altmann law as inevitable is 
seriously flawed.