The significance of these epidemiological studies is, however, limited because of the small number of participants, mostly males due to the working structure in the companies, and the problematic classification of exposure [17, 115].
But this rationale is also problematic, since classifications of desirable/undesirable species vary (Beinart and Middleton 2004: 16 18; Kendle and Rose 2000: 24; Milton 2000: 230–231), and 'exotic introductions are often woven into people's sense of place,' providing food and livelihoods (Warren 2007: 434).
Problematic rock classification criteria used in civil engineering require correction.
Consequently, classification of artifacts certainly including musical instruments—is far more problematic than biological classification.
Additionally, the variety of objects makes classification problematic.
Data sets in which there are many more observations in one class than another are problematic for many classification methods.
While the placement of a variety like Alasha, which is under the cultural influence of Inner Mongolia but historically tied to Oirat, and of other border varieties like Darkhad would very likely remain problematic in any classification, the central problem remains the question of how to classify Chakhar, Khalkha, and Khorchin in relation to each other and in relation to Buryat and Oirat.
7 Clinical development of new DED treatments is slow, partly because of problematic diagnosis and classification.
Our reconstruction of ancestral states within the Circumdehiscentiae shows that some previously used diagnostic characters are problematic for taxon classification, despite previous efforts to clarify plesio- and apomorphies [ 86, 88].
Classification only based on morphology may be problematic, and a true classification should be determined using the internal genes of the whole genome, coupled with the complex environmental factors.
