Here again is the data on expense ratio (%) for a sample of 20 large-cap blended mutual funds introduced in Exercise 1.53:
A normal probability plot shows a distinctly nonlinear pattern, primarily because of the single outlier on each end of the data. But a dotplot and boxplot exhibit a reasonable amount of symmetry. Assuming a symmetric population distribution, does the data provide compelling evidence for concluding that the population mean expense ratio exceeds 1%? Use the Wilcoxon test at significance level. 1.
Exercise 1.53: A mutual fund is a professionally managed investment scheme that pools money from many investors and invests in a variety of securities. Growth funds focus primarily on increasing the value of investments, whereas blended funds seek a balance between current income and growth. Here is data on the expense ratio (expenses as a % of assets, from www .morningstar.com) for samples of 20 large-cap balanced funds and 20 large-cap growth funds ("largecap" refers to the sizes of companies in which the funds invest; the population sizes are 825 and 762, respectively):
Calculate and compare the values of x, ,x , and s for the two types of funds.
b. Construct a comparative boxplot for the two types of funds, and comment on interesting features