Can measurements of the petal length of flowers be of value when you need to determine the species of a certain flower? Here are the summary statistics from measurements of the petals of two species of irises. (R. A. Fisher, The Use of Multiple Measurements in Axonomic Problems. Annals of Eugenics 7 [1936]:179 188)
|
Species |
|
Versicolor |
Virginica |
| Count |
50 |
50 |
| Mean |
55.52 |
43.22 |
| Median |
55.5 |
44 |
| SD |
5.519 |
5.362 |
| Min |
45 |
30 |
| Max |
69 |
56 |
| Lower Quartile |
51 |
40 |
| Upper Quartile |
59 |
47 |
a) Make parallel boxplots of petal lengths for the two species.
b) Describe the differences seen in the boxplots.
c) Write a 95% confidence interval for this difference.
d) Explain what your interval means.
e) Based on your confidence interval, is there evidence of a difference in petal length? Explain.