A statistician for the Boston Police Department developed forecasts of monthly armed robberies in Boston from June 1974 to May 1975 using two forecasting methods, model A and model B. Her forecasts, absolute forecast errors, and squared forecast errors for both forecasting techniques, along with the actual time series, are displayed in the following table. The time series plot of the data is shown under the table. (Data source: Time Series Data Library.) Model A Model B Armed Absolute Squared Absolute Squared Month Robberies Forecast Forecast Error Forecast Error Forecast Forecast Error Forecast Error June 1974 287 July 355 321.0 34.00 1156.00 355.00 0.00 0.00 August 460 407.5 52.50 2756.25 355.00 105.00 11025.00 September 364 412.0 48.00 2304.00 364.00 0.00 0.00 October 487 425.5 61.50 3782.25 364.00 123.00 15129.00 November 452 469.5 17.50 306.25 452.00 0.00 0.00 December 391 421.5 30.50 930.25 452.00 61.00 3721.00 January 500 445.5 54.50 2970.25 452.00 48.00 2304.00 1975 February 451 475.5 24.50 600.25 452.00 1.00 1.00 March 375 413.0 38.00 1444.00 451.00 76.00 5776.00 April 372 373.5 1.50 2.25 375.00 3.00 9.00 May 302 337.0 35.00 1225.00 372.00 70.00 4900.00 Sum 397.50 17,476.75 487.00 42,865.00\fThe exchange rate between two currencies is the value of one currency in terms of the other. Daily time-series data for the exchange rate between the U.S. dollar and the euro (the common currency used by many European countries) is stored in the data set named Exchange Rates in the DataView tool that follows. The exchange rate is expressed as euros per U.S. dollar. The data set includes three variables: yt (exchange rates from 11/12/2008 to 4/30/2009), yt_1 (exchange rates from 11/11/2008 to 4/29/2009), and St_1 (exponentially smoothed exchange rates from 11/11/2008 to 4/29/2009, with smoothing constant w = 0.1). Data Set Exchange Rates Sample Variables = 3 Observations = 169 USD expressed in EUR's 11/13/08 to 4/30/09 www.exchange-rates.org Variables Observations Variable V Type V Form V Values V Missing Observations y_t Quantitative Numeric 169 y_(t-1) Quantitative Numeric 169 ooo S_(t-1) Quantitative Numeric 169 Variable Variable Variable Correlation Correlation