Assignment A

The data on technology firms from BusinessWeek measure company performance for the year 2009.

A. Observe the sample and describe the population the sample was likely taken from.

B. Divide the sample into Asian and non-Asian firms. Include as Asian: China, Hong Kong, India, Japan, Singapore, Korea, and Taiwan. Calculate and compare the mean operating income level for the two groups. Can we say for sure that the population mean operating income for Asian firms is different from non-Asian firms? Explain.

C. Calculate and interpret the standard deviation in operating income for Asian and non-Asian firms. Calculate and interpret the coefficient of variation for the two groups. Which type of firm exhibits greater variation in operating income? Does the comparison of standard deviations tell the same story as the comparison of the coefficients of variation? Explain.

D. Generate the distribution in operating income for the full sample of firms. Use eight classes in the distribution. Set the size of each class at $2,801 million. Make the endpoint of the first class equal to $2,834 million. Graph the distribution and discuss its skewness.

E. Test the assumption that the average firm within the population had a mean operating income of 1.5 billion dollars. Construct a 99% confidence interval for the population mean operating income and discuss whether your statistics agree or disagree with the assumption.