The authors of the article “Dynamics of Canopy Structure and Light Interception in Pinus...

The authors of the article “Dynamics of Canopy Structure and Light Interception in Pinus elliotti, North Florida” (Ecological Monographs, 1991: 33–51) planned an experiment to determine the effect of fertilizer on a measure of leaf area. A number of plots were available for the study, and half were selected at random to be fertilized. To ensure that the plots to receive the fertilizer and the control plots were similar, before beginning the experiment tree density (the number of trees per hectare) was recorded for eight plots to be fertilized and eight control plots, resulting in the given data. Minitab output follows.

a. Construct a comparative boxplot and comment on any interesting features.

b. Would you conclude that there is a significant difference in the mean tree density for fertilizer and control plots? Use α = 05.

c. Interpret the given confidence interval.