1. Plot the raw data on arrivals for each transportation mode against time, all on the same graph. Which mode is growing the fastest? Which the slowest?
2. Plot the logarithm of arrivals for each transportation mode against time, all on the same graph. Which now appears to be growing the fastest? Logarithms are especially useful for comparing series with two divergent scales since 10 percent growth always looks the same, regardless of the starting level. When absolute levels matter, the raw data are more appropriate, but when growth rates are what€™s important, log scales are better.
3. Now create an index number to represent the growth of arrivals in each transportation mode by dividing the first (smallest) number in each column into the remaining numbers in the column. Plot these index numbers for each transportation mode against time, all in the same graph. Which is growing the fastest?
4. In attempting to formulate a model of the passenger arrival data on cruise ships over time, would a nonlinear (perhaps a multiplicative exponential) model be preferable to a linear model of cruise ship arrivals against time? What about in the case of the passenger arrivals by ferry against time?
5. Estimate the double-log (log linear) time trend model for log cruise ship arrivals against log time. Estimate a linear time trend model of cruise ship arrivals against time. Calculate the root mean square error between the predicted and actual value of cruise ship arrivals. Is the root mean square error greater for the double log time trend model or for the linear time trend model?

The summer months bring warm weather, mega fauna (bears), and tourists to the coastal towns of Alaska. Skagway at the top of the Inland Passage was, in the nineteenth century, the entrance to the Yukon. Today this town attracts multiple cruise ships per day; literally thousands of passengers disembark into a town of 800 for a taste of the Alaskan frontier experience between 10 a.m. and 5 p.m. Some ride steam trains into the mountains while others wander the town spending money in galleries, restaurants, and souvenir shops. The Skagway Chamber of Commerce is trying to decide which transportation mode in the table of visitor arrival statistics should receive the highest priority in the tourist promotions for nextseason.

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