The data in the following table, represent the annual incidence rates (per 100,000 persons) of reported acute poliomyelitis recorded over five-year periods from 1915 to 1955:

Year191519201925193019351940194519501955__________________________________________________________

Rate3.12.25.37.58.57.410.322.117.6

Source: Data extracted from B. Wattenberg, Ed., The Statistical History of the United States: From Colonial Times to the Present, ser. B303.

a. Plot the data.

b. Compute the linear trend forecasting equation and plot the trend line.

c. What are your forecasts for 1960, 1965, and 1970?

d. Using a library or the Internet, find the actually reported incidence rates of acute poliomyelitis for 1960, 1965, and 1970. Record your results.

e. Why are the forecasts you made in (c) not useful? Discuss.