The file P12_12.xlsx contains five years of monthly data on sales (number of units sold) for a particular company. The company suspects that except for random noise, its sales are growing by a constant percentage each month and will continue to do so for at least the near future. a. Explain briefly whether the plot of the series visually supports the company's suspicion. An exponential fit looks reasonable. The graph of sales linear. b. Fit the appropriate regression model to the data. Report the resulting equation. Let X represent the time index. Round your answer to three decimal places, if necessary. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank. (Example: -300) RMSE MAPE Log() V State explicitly what it says about the percentage growth per month. Round your answer to one decimal place, if necessary The equation implies an approximate 2.6 % increase per month. c. What are the RMSE and MAPE for the forecast model in part b? Round your answers to two decimal places, if necessary. = 8.662 shows some sign of increasing at an increasing rate, but the graph of Log(sales) is nearly + 0.026 X %6 In words, what do they measure? RMSE measures the square root of the average square MAPE measures the average absolute percentage forecast error. d. Given the forecast value for the last month in the data set, what simple arithmetic could you use to obtain forecasts for the next few months? Round your answer to four decimal places, if necessary. Starting with the last forecast value for month 60, multiply each forecasted value by forecast error. to obtain the next one.

The file P12_12. viex contains five years of monthly data on sales (number of units sold) for a particular company. The compary suspects that except for random. norse, its sales are growing by a constant percentage each month and will continue to do so for at least the near future. a. Explain briefly whether the plot of the series visually supports the company's suspicion. hit looks reasonable. The graph of shows some sign of increasing at an increasing rate, but the graph of is nearly linear. b. It the approprate regression model to the data. Report the resulting equation. Let X represent the tirve indox: Round your answer to three decimal places; if necessary. for subtractive or negative numbers use a minus sign even if there is a + sign before the blank, (texample:) 300) State expliotly what it says about the perceotage growth per month. flound your answer to one decimal place, if necessary The equation implies an approximate % increase per month. c. What are the RMSt and MAPt. for the forecast moded in part b? Round your answers to two decamal places, if necessary: IMSE MAPC In words, what do they measure? PMSt measutes the torecast error: MMie-measures the forecast error d. Given the forecast value for the last moeth in the data set, what umple arithmetec could you use to obtain forecaits for the nent fee inanths? Round rouit arswer to four decamal plachs, if necessary. Starting with the last forecast value for month 60 . each forecasted yalue by to abtain the nevt one. The file P12_12. viex contains five years of monthly data on sales (number of units sold) for a particular company. The compary suspects that except for random. norse, its sales are growing by a constant percentage each month and will continue to do so for at least the near future. a. Explain briefly whether the plot of the series visually supports the company's suspicion. hit looks reasonable. The graph of shows some sign of increasing at an increasing rate, but the graph of is nearly linear. b. It the approprate regression model to the data. Report the resulting equation. Let X represent the tirve indox: Round your answer to three decimal places; if necessary. for subtractive or negative numbers use a minus sign even if there is a + sign before the blank, (texample:) 300) State expliotly what it says about the perceotage growth per month. flound your answer to one decimal place, if necessary The equation implies an approximate % increase per month. c. What are the RMSt and MAPt. for the forecast moded in part b? Round your answers to two decamal places, if necessary: IMSE MAPC In words, what do they measure? PMSt measutes the torecast error: MMie-measures the forecast error d. Given the forecast value for the last moeth in the data set, what umple arithmetec could you use to obtain forecaits for the nent fee inanths? Round rouit arswer to four decamal plachs, if necessary. Starting with the last forecast value for month 60 . each forecasted yalue by to abtain the nevt one