Analysis Summary
Data variable: AUTOADJ/CPI
Number of observations = 314
Start index = 1/70
Sampling interval = 1.0 month(s)
Length of seasonality = 12
Forecast Summary
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Forecast model selected: Constant mean = 1.40164 + 1 regressor
Number of forecasts generated: 0
Number of periods withheld for validation: 26
Estimation Validation
Statistic Period Period
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MSE 4.10166 10.6607
MAE 1.64644 3.05438
MAPE 8.3251 9.9606
ME -1.43836E-14 3.05438
MPE -1.041 9.9606
Trend Model Summary
Parameter Estimate Stnd. Error t P-value
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Constant 1.40164 0.709646 1.97513 0.049215
INCOME/CPI 0.0782192 0.0028257 27.6814 0.000000
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The StatAdvisor
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This procedure will forecast future values of AUTOADJ/CPI. The
data cover 314 time periods. Currently, a mean model has been
selected. This model assumes that the best forecast for future data
is given by the average of all previous data. You can select a
different forecasting model by pressing the alternate mouse button and
selecting Analysis Options.
The output summarizes the statistical significance of the terms in
the forecasting model. Terms with P-values less than 0.05 are
statistically significantly different from zero at the 95% confidence
level. In this case, the P-value for the mean is less than 0.05, so
it is significantly different from 0.0. The model also includes one
independent regression variable. Since INCOME/CPI has a P-value which
is less than 0.05, it is statistically significant at the 95%
confidence level.
The table also summarizes the performance of the currently selected
model in fitting the previous data. It displays:
(1) the mean squared error (MSE)
(2) the mean absolute error (MAE)
(3) the mean absolute percentage error (MAPE)
(4) the mean error (ME)
(5) the mean percentage error (MPE)
Each of the statistics is based on the one-ahead forecast errors,
which are the differences between the data value at time t and the
forecast of that value made at time t-1. The first three statistics
measure the magnitude of the errors. A better model will give a
smaller value. The last two statistics measure bias. A better model
will give a value close to 0.0. In this case, the model was estimated
from the first 288 data values. 26 data values at the end of the time
series were withheld to validate the model. The table shows the error
statistics for both the estimation and validation periods. If the
results are considerably worse in the validation period, it means that
the model is not likely to perform as well as otherwise expected in
forecasting the future.