Refer to the data in Exercise 42 of Section 7.4.
a. Use a smoothing parameter of .5 to create a kernel density plot for this data.
b. Repeat part (a) using a smoothing parameter of .3.
c. Which of the plots in parts (a) and (b) appears to fit the data better?
The article “Measuring and Understanding the Aging of Kraft Insulating Paper in Power Transformers” (IEEE Electrical Insul. Mag., 1996: 28–34) contained the following observations on degree of polymerization for paper specimens for which viscosity times concentration fell in a certain range:
a. Construct a boxplot of the data and comment on any interesting features.
b. Is it plausible that the given sample observations were selected from a normal distribution?
c. Calculate a two-sided 95% confidence interval for true average degree of polymerization (as did the authors of the article). Does the interval suggest that 440 is a plausible value for true average degree of polymerization? What about 450?