24 Irises Can measurements of the petal length of flowers b

24. Irises - 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. a) Make parallel boxplots of petal length for the two species b) Describe the differences seen in the boxplot. 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.

Data

Versicolor = Count - 50, Mean - 55.52, Median - 55.50, SD - 5.519, Min - 45, Max - 69, Lower Quartile - 51, Upper Quartile - 59,

Virginica = Count - 50, Mean 43.22, Median - 44.00, SD - 5.362, Min - 30, Max - 56, Lower Quartile - 40, Upper Quartile - 47

Solution

c) Write a 95% confidence interval for this difference.

95% CI for difference: (10.14, 14.46)

d) Explain what your interval means.

in 95% cases the difference of the two sample mean should fall in the region  (10.14, 14.46)

e) Based on your confidence interval, is there evidence of a difference in petal length? Explain.

for sample Difference = mu (1) - mu (2)
Estimate for difference: 12.30

hence the difference of samples fall in the region (10.14, 14.46). but accoding to testing proccedure we get p-value as 0.00001 < 0.05 so we claim that the two groups mean are differ significantly