title: Quantitative methods in ethnobotany and ethnopharmacology: considering the overall flora--hypothesis testing for over- and underused plant families with the Bayesian approach.
abstract: BACKGROUND
  We introduce and explain the advantages of the Bayesian approach and exemplify the method with an analysis of the medicinal flora of Campania, Italy. The Bayesian approach is a new method, which allows to compare medicinal floras with the overall flora of a given area and to investigate over- and underused plant families. In contrast to previously used methods (regression analysis and binomial method) it considers the inherent uncertainty around the analyzed data.
  
  
  METHODS
  The medicinal flora with 423 species was compiled based on nine studies on local medicinal plant use in Campania. The total flora comprises 2237 species belonging to 128 families. Statistical analysis was performed with the Bayesian method and the binomial method. An approximated χ(2)-test was used to analyze the relationship between use categories and higher taxonomic groups.
  
  
  RESULTS
  Among the larger plant families we find the Lamiaceae, Rosaceae, and Malvaceae, to be overused in the local medicine of Campania and the Orchidaceae, Caryophyllaceae, Poaceae, and Fabaceae to be underused compared to the overall flora. Furthermore, do specific medicinal uses tend to be correlated with taxonomic plant groups. For example, are the Monocots heavily used for urological complaints.
  
  
  CONCLUSIONS
  Testing for over- and underused taxonomic groups of a flora with the Bayesian method is easy to adopt and can readily be calculated in excel spreadsheets using the excel function Inverse beta (INV.BETA). In contrast to the binomial method the presented method is also suitable for small datasets. With larger datasets the two methods tend to converge. However, results are generally more conservative with the Bayesian method pointing out fewer families as over- or underused.
authors.affiliation: Institute of Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland.
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Weckerle
authors.forename: Stefano
authors.initials: S
authors.lastname: Cabras
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: Castellanos
authors.forename: Marco
authors.initials: M
authors.lastname: Leonti
mesh_terms: D001499:Bayes Theorem; D044822:Biodiversity; D016009:Chi-Square Distribution; D019448:Ethnobotany / Q000706:statistics & numerical data*; D020834:Ethnopharmacology / Q000706:statistics & numerical data*; D007558:Italy; D015233:Models, Statistical; D028321:Plant Preparations / Q000627:therapeutic use*; D010946:Plants, Medicinal / Q000145:classification*; D035501:Uncertainty
chemical_list: D028321:Plant Preparations