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This app will compute a CurviLinear Regression for a series of x, y coordinates. The general equation form for a curvilinear regression is:

**y = b(0) + b(1)x + b(2)x^2 + b(3)x^3 + b(4)x^4 + b(5)x^5 + b(6)x^6**

where

y is the dependent variable

x is the independent variable and

b() are the calculated coefficients

Note that there is just one independent variable (x). The degree of polynomial can vary from 2 to 6, and is user selectable. Taking x to a power provides the curvature in the regression line. You will seldom have to go beyond a fourth power, and may lose accuracy at a higher power.

This app allows for an infinite number of data points for each regression. Example datasets are included to help users get started quickly. These examples serve as guides for organizing and entering data. You can turn these examples off under * Preferences*. A main menu provides the organizational structure for this app. From this menu you can choose to start a new project, work on an existing project (such as data entry), or produce tables and graphs for a project. Menu items can also be reached from buttons on the toolbar.

Each new regression is organized as a project. This organizational structure follows throughout all of the regression and ANOVA apps in the **Computational Suite**. New projects are created by assigning a unique ID to the project. After entering the ID you can enter details associated with the project along with x, y data pairs. Data can be entered manually or from a comma delimited text file.

Reports include the regression variables, data frequency and residuals. If you have made any data entry errors, simply go back and correct them, then click on the reports menu item again. Reports can also be sent to a text file if you need to insert them into a word processing document such as Apple Pages or MS Word.

Both 2D and 3D graphics are available. You can test the sensitivity of the beta coefficients with the up/down arrows. For the 3D graph, use the Zoom, Yaw, Pitch and Roll controls to see the entire graph from different angles.

This app is also equipped with an automatic backup system. Each time you quit the app a backup copy is generated. Up to 1000 backup copies are kept. To restore a project from a prior backup, select the last menu item and follow the instructions.