
Here we see number of soldiers killed, day-by-day, in 2006. Average deaths per day: 2.187. Now suppose we run a regression to find the trend increase in the cumulative count, then use the regression equation to forecast the total number of deaths for the next few months. The regression equation is
Cumulative deaths = 2161.63 + 2.10726*TREND
The regression equation predicts we break the 3000 barrier on February 3. But if you look at the data closely, you will notice a small increase in the number of deaths per day. Let's account for this by assuming a quadratic trend. We get:
Cumulative deaths = 2202.925 + 1.399359*TREND + 0.002017*TREND^2
Note the much superior fit. In fact, coefficients on both trend terms are statistically significant at extremely low significance levels. There does indeed seem to be an increasing trend. This equation forecasts the 3000th death to occur on January 8. Happy freakin' New Year.
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