Question: 62 Concentration of trace elements. Vanadium (V) is a recently recognized essential trace element. An experiment was conducted to compare the concentrations of V in bio­logical materials using isotope dilution mass spectrometry (Analytical Chemistry, Nov. 1985). The accompanying

table gives the quantities of V (measured in nanograms per gram) in dried samples of oyster tissue, citrus leaves, bovine liver, and human serum.

a. Identify the treatments in this experiment.

b. Is there sufficient evidence (at a = .05) to indicate that the mean V concentrations differ among the four bio­logical materials?

c. If appropriate, use a multiple comparisons procedure to rank the treatment means at \(\alpha \) = .06.