Stat > Time Series > Forecast with Best ARIMA Model > Graphs
The graphs are for the model that the analysis identifies as the best model.
Autocorrelation function (ACF) plot of residuals
Display the autocorrelation function (ACF) for the residuals. Use this
plot to verify that the residuals are not correlated. The presence of
autocorrelated residuals indicates that you may need to modify the model terms.
Partial autocorrelation function (PACF) plot of residuals
Display the partial autocorrelation function (PACF) for the residuals.
Use this plot to verify that the residuals are not correlated. The presence of
autocorrelated residuals indicates that you may need to modify the model terms.
Time series plot
Specify whether Minitab displays a time series plot. If the analysis
uses a transformation, the results include plots for the original series and
the transformed series.
Stamp column for time scale
Enter a column that contains the x-axis labels for the time
series plot.
Residuals for the following plots
Select whether to use standardized or regular residuals for the
following residual plots. Usually, you use standardized residuals because the
assumption that the residuals follow a normal distribution provides guidelines
for when a standardized residual is unusually large, such as greater than 2 and
less than -2. For more information on types of residuals, go to
Which types of residuals are included in Minitab?.
Individual
plots
Select to choose which residual plots to include.
Histogram of
residuals
Display the shape and spread of the residuals. Use the histogram
of residuals to determine whether the data are skewed or whether outliers exist
in the data.
Normal plot of
residuals
Display a normal probability plot of the residuals. Use the
normal plot of residuals to determine whether the residuals are normally
distributed.
Residuals versus
fits
Display the residuals versus the fitted values. Use the residuals
versus fits plot to determine whether the residuals are unbiased and have a
constant variance.
Residuals versus
order
Display the residuals versus the order of the data. The row
number for each data point is shown on the x-axis. Use the residuals versus
order plot to see how accurate the fitted values are compared to the observed
values during the observation period.
Four in one
Select to display all four residual plots together in one graph.
Residuals versus the
variables
Enter one or more variables to plot versus the residuals. Use the
residuals versus the variables plot to assess whether a variable that is not in
the analysis systematically affects the response.
