Yes, and I will write in detail about this in the next post. Testing for deviations from Hardy-Weinberg proportions are usually made to check if there is a random mating present in populations with respect to a particular locus. If we know all the genotypes and allele types present in a population gene pool, we can easily calculate predicted, hypothetical (H-W) frequencies. After that, geneticists collect actual data and calculate observed, real frequencies of alleles and genotypes. The difference between predicted and observed frequencies is deviation from H-W. We know what events influence allele frequencies and in what way, so conclusion why the frequencies are changed can be made. For example, non-random mating increases frequency of the homozygous genotypes, which means that has an influence on genotype frequencies, however, it doesn't change allele frequencies. Unlike non-random mating, genetic drift ( sampling error from generation to generation, strong influence in small populations) will change the allele frequencies, which leads to deviations of H-W principle. All this with more math in the next post! :)