Working with Equations

An equation is used to calculate the output variables by transforming the input variables with statistical and mathematical methods. Calculations are executed taking into account calendar frequency of the model (years, half-years, quarters, months and days).

In the web application, the equation is a set of variables, bound together. Each variable may have multiple links. To work with equation, select it or one of its links in the working area and use ribbon commands and side panel tabs.

Creating an equation requires creating a link between variables. Creating a link is described in detail in the Creating an Equation section.

To open an equation with the definite key:

Open the browser.
In the address bar specify the Modeling and Forecasting tool URL in the web application. The unit address is created as follows: <URL of web application>/model.html.
For example: http://biserver/fp_App_v9.2/app/model.html, where «http://biserver/fp_App_v9.2/app» is the web application URL.
Add the key special parameter to the URL and specify the model key. Then add the entry special parameter and specify the equation key. URL format: <tool URL>#key=<model key>&entry=<equation key>. If it is required to open several equations, determine their keys via comma.
For example: http://biserver/fp_App_v9.2/app/model.html#key=11111&entry=12345,67890, where 11111 is the model key, 12345 and 67890 are keys of equations to be opened.
Open the formed URL.

The model containing the equation is displayed it the working area. The opened equation is selected.

If the model or equation with the specified key is not found, the corresponding message appears. The model and equation are searched in repository, specified in the PP.xml file for the web application in use.

To save an equation:

Select the Save item in the Model main menu.
Press CTRL+S. The key combination is available if there are no opened dialog boxes in the working area.
Click the button next to the Model main menu.

The entire model is saved, into which this equation is included.

To delete an equation, delete all the variables links forming the model. Select a link (to select multiple links, hold down the CTRL key), then:

Press the DELETE key.
Click the Delete button on the Home ribbon tab.

To set up equation parameters, use side panel tabs. Tabs set depends on the equation type. This set always includes the Equation tab that is used to set up basic parameters of equation. For details see the Setting Up Equation Parameters section.

To change equation type:

Make sure that the side panel is displayed.
Select output variable or one of the equation links.
Go to the Equation tab and in the Equation Type drop-down list select the required equation type.

The equation is rebuilt according to the selected equation type.

On changing the type of equation included into the equation system, take into account the following features:

If the selected equation type is a non-factor one and cannot be used in the equation system, it is prompted to change equation type and exclude it from the system or keep the equation type without changes.
If the selected equation type is a factor one and cannot be used in the equation system, it is prompted to change equation type or transform the system into a cycle or keep the equation type without changes.

A criterion function can be created for the equation, the function enables the user to calculate the criterion problem and optimal control problem. Detailed description of the process of creating criterion function is given in the Setting Up Criterion Function section.

An equation is calculated automatically. If errors or warnings occurred during the equation calculation, they are displayed on the Errors results panel tab.

Equation calculation results are displayed on results panel tabs:

Specification.
Graphs.
Table.
Factors.
Summary Statistics.
Correlation Matrix.
Characteristic Roots of AR and MA Processes.
Weight Matrix.
ACF and PACF.
Errors.

Displayed tabs depend on the calculation method in use.

Diagnostic tests are used to check linear regression model for violation of fundamental hypothesis. The tests also help check whether regression model is specified correctly.

To run tests, select the output variable or one of the links in the linear regression equation. Calculation results are shown on the Diagnostic Tests tab on the results panel.

The equation key is unique and used for single-valued identification of an equation within the modeling container.

To get the equation key:

Open the model containing the equation.
Select the output variable or one of the equation links. To get keys of several equations, select several output variables or links of several equations.
Go to the browser address bar.

The equation key is shown in the web application URL after the entry special parameter. If several equations are selected, their keys are specified via comma. For example: http://biserver/fp_App_v9.2/app/model.html#key=11111&entry=12345, where 12345 is the equation key.