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Business Forecasting

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Content Introduction 1 Part 1. Examine the data, looking for seasonal effects, trends and cycles 2 Part2. Dummy Variables Model 3 Linear trend model 3 Quadratic trend model 5 Cubic trend model 7 Part 3. Decomposition and Box-Jenkins ARIMA approaches 8 First difference: 10 a. Create an ARIMA (4, 1, 0) model 10 b. Create an ARIMA (0, 1, 4) model 11 c. Create an ARIMA (4, 1, 4) 11 d. Model overfitting 12 Second difference 13 Forecast based on ARIMA (0, 1, 4) model 13 Return the seasonal factors for forecasting 14 Part 4. Discussion of different methods and the results 15 Comparison of different methods in terms of time series plot 15 Comparison of different models in terms of error 17 Assumptions and the …show more content…

Therefore, this linear model is not good and it may be enhanced by non-linear models. Quadratic trend model A new dummy variable TIME2 is created in this model (TIME2= TIME*TIME). The equation of this model is: Data=a+ c1 time +c2 (time) 2 + b1Q1+b2Q2+b3Q3+ error The regression model is built up with Stepwise method as well, and the output is simplified and only the useful model is left. The significance of Q2 and Q3 is over 0.05 through F-test therefore being removed from the model. The adjusted R square is 97% which shows a good fit and better than the linear model. To build the Quadratic trend model according to the output: Trend-cycle = 11698.512 + 1297.080*TIME – 9.143* TIME2 – 1504.980* Q1 + error Model Summaryd | Model | R | R Square | Adjusted R Square | Std. Error of the Estimate | 3 | .986c | .971 | .970 | 2275.62420 | a. Predictors: (Constant), TIME, TIME2, Q1b. Dependent Variable: creditlending | Coefficientsa | Model | Unstandardized Coefficients | Standardized Coefficients | t | Sig. | | B | Std. Error | Beta | | | 3 | (Constant) | 11698.512 | 946.957 | | 12.354 | .000 | | TIME | 1297.080 | 74.568 | 1.643 | 17.395 | .000 | | TIME2 | -9.143 | 1.246 | -.693 | -7.338 | .000 | | Q1 | -1504.980 | 700.832 | -.050 | -2.147 | .036 | a. Dependent Variable: creditlending | As you can see on the sequence chart displayed above, this model is not very good as well. First of all, the model fit the modelling data

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