Assignment D

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 firms involved in hardware* and those that are not. Calculate and compare the mean revenue level for the two groups. Can we say for sure that the population mean revenue for hardware firms is different from non-hardware firms? Explain.

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

D. Generate the distribution in revenue for the full sample of firms. Use eight classes in the distribution. Set the size of each class at $13,413.38 million. Make the endpoint of the first class equal to $13,914.38 million. Graph the distribution and discuss its skewness.

E. Test the assumption that the average firm within the population had a mean revenue of 7.45 billion dollars. Construct a 99% confidence interval for the population mean revenue and discuss whether your statistics agree or disagree with the assumption.

* Hardware includes the sectors: Communications; Computers, peripherals; Distributors; Electronic equipment; Semiconductors, equipment.