## Estimate Vector Error-Correction Model Using Econometric Modeler

This example models the annual Canadian inflation and interest rate series by using the Econometric Modeler app. The example shows how to perform the following actions in the app:

Test each raw series for stationarity.

Test for cointegration and determine a Johansen cointegration form if cointegration is present.

Fit several completing vector error-correction (VEC) models, and choose the one with the best, parsimonious fit.

Diagnose each residual series.

Export the chosen model to the command line.

At the command line, the example uses the model to generate forecasts.

The data set, which is stored in `Data_Canada`

, contains annual
Canadian inflation and interest rates from 1954 through 1994.

### Load and Import Data into Econometric Modeler

At the command line, load the `Data_Canada.mat`

data
set.

`load Data_Canada`

At the command line, open the **Econometric Modeler** app.

econometricModeler

Alternatively, open the app from the apps gallery (see **Econometric
Modeler**).

Import `DataTimeTable`

into the app:

On the

**Econometric Modeler**tab, in the**Import**section, click the**Import**button .In the Import Data dialog box, in the

**Import?**column, select the check box for the`DataTimeTable`

variable.Click

**Import**.

The Canadian interest and inflation rate variables appear in the
**Time Series** pane, and a time series plot of all the
series appears in the **Time Series Plot(INF_C)** figure
window.

Plot only the three interest rate series `INT_L`

,
`INT_M`

, and `INT_S`

together. In the **Time Series** pane, click
`INT_L`

and **Ctrl**+click
`INT_M`

and `INT_S`

. Then,
on the **Plots** tab, in the **Plots**
section, click **Time Series**. The time series plot
appears in the **Time Series(INT_L)** document.

The interest rate series each appear nonstationary, and they appear to move together with mean-reverting spread. In other words, they exhibit cointegration. To establish these properties, this example conducts statistical tests.

### Conduct Stationarity Test

Assess whether each interest rate series is stationary by conducting Phillips-Perron unit root tests. For each series, assume a stationary AR(1) process with drift for the alternative hypothesis. You can confirm this property by viewing the autocorrelation and partial autocorrelation function plots.

Close all plots in the right pane, and perform the following procedure for
each series `INT_L`

, `INT_M`

,
and `INT_S`

.

In the

**Time Series**pane, click a series.On the

**Econometric Modeler**tab, in the**Tests**section, click**New Test**>**Phillips-Perron Test**.On the

**PP**tab, in the**Parameters**section, in the**Number of Lags**box, type`1`

, and in the**Model**list select**Autoregressive with Drift**.In the

**Tests**section, click**Run Test**. Test results for the selected series appear in the**PP(**tab.)`series`

Position the test results to view them simultaneously.

All tests fail to reject the null hypothesis that the series contains a unit root process.

### Conduct Cointegration Test

To create and estimate a VEC model of unit root series, the series need to
exhibit cointegration. Conduct a Johansen test. Because the raw series do not
contain a linear trend, assume that the only deterministic term in the model is
an intercept in the cointegrating relation (`H1*`

Johansen form), and include 1 lagged difference term in the model.

In the

**Time Series**pane, click`INT_L`

and**Ctrl**+click`INT_M`

and`INT_S`

.In the

**Tests**section, click**New Test**>**Johansen Test**.On the

**JCI**tab, in the**Parameters**section, in the**Number of Lags**box, type`1`

. In the**Model**list, select**H1***.In the

**Tests**section, click**Run Test**. Test results and a plot of the cointegration relation for the largest rank appear in the**JCI**tab.

Econometric Modeler conducts a separate test for each cointegration rank 0
through 2 (the number of series – 1). The test rejects the null hypothesis of no
cointegration (**Cointegration rank** = 0), but fails to reject
the null hypothesis of **Cointegration rank** ≤ 1. The
conclusion is to set the cointegration rank of the VEC model to 1.

### Estimate VEC Models

Estimate 3-D VEC(* p*) models of the interest rate
series, with a cointegration rank of 1 and

*= 1 and 2.*

`p`

With

`INT_L`

,`INT_M`

, and`INT_S`

selected in the**Time Series**pane, in the**Models**section, click**VEC**.In the VEC Model Parameters dialog box, in the

**Johansen Form**, select**H1***. Fit the VEC(1) model by clicking**Estimate**.The model variable

`VEC`

appears in the**Models**pane, its value appears in the**Preview**pane, and its estimation summary appears in the**Model Summary(VEC)**document.Repeat steps 1 and 2 for the short-run polynomial order

= 2.`p`

Similar to the VEC(1) estimation, the variable

`VEC2`

appears in the**Models**pane, and its estimation summary appears in the**Model Summary(VEC2)**document. You can view properties of an estimated model in the**Preview**pane by clicking the model in the**Models**pane. For example, click`VEC`

.

### Select Model with Best In-Sample Fit

The estimation summary in each **Model
Summary(VEC** tab contains a plot
of fitted values and residuals, with respect to the time series in the

`p`

)**Time Series**list, a standard statistical table of estimates and inferences, and a table of information criteria.

Compare the information criteria of each estimated model simultaneously by positioning the estimation summary documents so that they occupy the left and right sections of the right pane. The model with the lowest value has the best, parsimonious fit.

The VEC(1) model `VEC`

produces the lowest AIC and
BIC values. Choose this model for further analysis.

### Check Goodness of Fit

Inspect the following VEC(1) plots of each residual series:

Histograms, for center, normality, and outliers

Quantile-quantile plots, for normality, skewness, and tails

Autocorrelation function (ACF), for serial correlation

ACF of squared residual series, for heteroscedasticity

This example diagnoses the residuals visually. Alternatively, you can conduct statistical tests to diagnose the residuals.

Dismiss the **Model Summary(VEC2)** document by clicking on its tab.

On the **Models** pane, click
`VEC`

.

Plot separate residual histograms. On the **Econometric
Modeler** tab, in the **Diagnostics** section,
click **Residual Diagnostics** > **Residual
Histogram**. Histograms of the each residual series appear in
the **Histogram(VEC)** document.

Each residual series appears approximately centered around 0 and approximately normal.

Plot separate residual quantile-quantile plots. With
`VEC`

selected in the **Time
Series** pane, on the **Econometric Modeler** tab,
in the **Diagnostics** section, click **Residual
Diagnostics** > **Residual Q-Q Plot**.
Quantile-quantile plots of each residual series appear in the
**QQPlot(VEC)** document.

The residual series are slightly skewed left and have lighter tails than the normal distribution. This example proceeds without addressing possible skewness and light tails.

Plot separate ACF plots of each residual series. With
`VEC`

selected in the **Time
Series** pane, on the **Econometric Modeler** tab,
in the **Diagnostics** section, click **Residual
Diagnostics** > **Autocorrelation
Function**. ACF plots of each residual series appear in the
**ACF(VEC)** document.

The residuals do not exhibit significant autocorrelation.

Plot separate ACF plots of each squared residual series. With
`VEC`

selected in the **Time
Series** pane, on the **Econometric Modeler** tab,
in the **Diagnostics** section, click **Residual
Diagnostics** > **Squared Residual
Autocorrelation**. ACF plots of each squared residual series
appear in the **ACF(VEC)2** document.

Each squared residual series has significant autocorrelations at early lags, which suggests that heteroscedasticity is present in all series. This example proceeds without addressing possible heteroscedasticity.

### Export Model to Workspace

Export the model to the workspace.

With the

`VEC`

model selected in the**Models**pane, on the**Econometric Modeler**tab, in the**Export**section, click**Export**>**Export Variables**.In the Export Variables dialog box, select the

**Select**check box for`INT_L`

,`INT_M`

, and`INT_S`

.Click

**Export**.

The variables `INT_L`

, `INT_M`

,
`INT_S`

, and `VEC`

appear in the
workspace.

### Generate Forecasts at Command Line

Generate forecasts and approximate 95% forecast intervals from the estimated
VEC(1) model for the next five years. For convenience, use the entire series as
a presample for the forecasts. The `forecast`

function
discards all specified presample observations except for the required final
observation.

Y0 = [INT_L INT_M INT_S]; [YF,YFMSE] = forecast(VEC,5,Y0); YFSE = cell2mat(cellfun(@(x)sqrt(diag(x)'),YFMSE,UniformOutput=false)); UB = YF + 1.96*YFSE; LB = YF - 1.96*YFSE; datesF = DataTimeTable.Time(end) + calyears(1:5); figure tiledlayout(3,1) for j = 1:VEC.NumSeries nexttile h1 = plot(DataTimeTable.Time,Y0(:,j),Color=[.75,.75,.75]); hold on h2 = plot(datesF,YF(:,j),"r",LineWidth=2); h3 = plot(datesF,UB(:,j),"k--",LineWidth=1.5); plot(datesF,LB(:,j),"k--",LineWidth=1.5); ct = [Y0(end,j) YF(1,j); Y0(end,j) LB(1,j); Y0(end,j) UB(1,j);]; plot([DataTimeTable.Time(end); datesF(1)],ct,Color=[.75,.75,.75]) legend([h1 h2 h3],VEC.SeriesNames(j),"Forecast", ... "Forecast interval",Location="northwest") hold off end