Sampling Bias in Ethnobotanical Studies on Medicinal Plants Conducted in Local Markets

Studies have identified the strong presence of sampling bias in ethnobiological research, which may seriously compromise study results. However, these studies were made in the context of Brazilian studies and global sampling evaluations are still needed. The present study adopted a global scale and was based on ethnobotanical surveys of medicinal plants in open fairs and markets. We aimed to assess sample quality and to identify the factors that interfere with it. Among the factors we investigated were how the (a) year of publication, (b) CiteScore, (c) presence of a clear research question, (d) presentation of hypotheses, and (e) the use of ethnobotanical indices influences the presence of sampling bias. The main source of bias verified in the studies was the absence of information about the sample and the population. None of the variables tested interfered with the level of bias of the studies. Efforts are needed to correct quantitative studies regarding sampling procedures, and the peer-review exercise in scientific journals should be attentive to sampling bias.