A promising new technology for generating electricity uses microbial fuel cells (MFCs)—a product of natural human wastewaters. Over the past several years, research in employing MFCs for this purpose has dramatically increased. The graph below, extracted from the Biochemical Engineering Journal (Vol. 73, 2013), summarizes the areas of investigation for a sample of 54 recently published research articles on MFCs. (Note: Each of the 54 articles was classified according to a particular area of investigation, e.g., microbial metabolism, biocathodes, patents, etc.)
a. Identify the qualitative variable measured for each research article.
b. What type of graph is portrayed?
c. Convert the graph into a Pareto diagram. Then, use the diagram to identify the investigation area with the largest proportion of MFC research articles.
