When you enter the **Regression** app, you must type your data in a two-column table.

- In the first column ($x_{i}$), enter the values of the first variable of your statistical data set.
- In the second column ($y_{i}$), enter the values of the second variable of your statistical data set.

Once you have entered your data in the table, you can plot a linear regression.

- Select the
**Graph**tab at the top of the screen. - Confirm by pressing
**OK**.

You then see the points that represent your data as well as the regression line that fits the model equation $y=ax+b$$. The $a$ and $b$ coefficients are displayed in the banner at the bottom of the screen.

Once you have typed your data into the table in the **Data** tab, you can display the statistical variables: mean, standard deviation, median,…

- Select the
**Stats**tab at the top of the screen. - Confirm by pressing
**OK**.

You then see the table of statistical variables.

You can delete a row from the table by selecting a cell in that row and pressing **DEL**.

You can change the content of a cell by selecting it and typing a new value with the keyboard.

You can delete all the values in a column of the table.

- Select the name of the column you want to clear. Confirm by pressing
**OK**. - The column options menu opens. Select
**Clear column**and confirm with**OK**.

Clearing the $x_{i}$ column also clears the $y_{i}$ column.

Clearing the $y_{i}$ column fills this column with the value $0$.

You can move the cursor using the four directional arrows:

**Left arrow**/**Right arrow**: move the cursor on the line to the right or left or from point to point.**Up arrow**/**Down arrow**: move the cursor from the data points to the regression line and vice versa.

You can look for a specific point on the regression line knowing its abscissa or ordinate: that is, you can predict a value of $X$ given $Y$ and a value of $Y$ given $X$.

- Move the cursor to the regression line and press
**OK**. - The regression line menu opens. Select
**Prediction given X**if you know the value of $X$ and**Prediction given Y**if you know the value of $Y$. Confirm by pressing**OK**. - Type your value, then select the
**Validate**button and press**OK**.

The cursor has moved to the desired point. You can read the coordinates of this point at the bottom of the screen.

To access the display window settings, select one of the options under the **Graph** tab and press **OK**.

You can choose between three options: **Axes**, **Zoom** and **Preadjustment**.

When you are in the graph display window, you can press the

+and-keys to zoom in/out.

In **Axes**, you can enter the values of **Xmin** and **Xmax** that define the width of your display window.

If **Yauto** is activated, the height of your display window will be automatically calculated to display all points of the curve between **Xmin** and **Xmax**. Otherwise, manually enter your **Ymin** and **Ymax** values.

Confirm by selecting the **Confirm** button and pressing **OK**.

Select **Zoom** to access an interactive display window setting:

**Left arrow**/**Up arrow**/**Right arrow**/**Down arrow**: move the window/*+***-**: zoom in/zoom out

The **Preadjustment** menu offers you 3 predefined display windows:

**Integer**: window in which the abscissa are integers**Orthonormal**: window displaying an orthonormal coordinate system**Basic settings**: reset the display window

The **Stats** tab displays the statistical variables calculated using the data in the **Data** tab:

- Mean of $x_{i}$ values and $y_{i}$
- Sum of $x_{i}$ and $y_{i}$
- Sum of the squares of $x_{i}$ and $y_{i}$
- Standard deviation of $x_{i}$ and $y_{i}$
- Variance of $x_{i}$ and $y_{i}$
- Number of data points
- Covariance
- Sum of $x_{i} \times y_{i}$
- Slope $a$ and y-intercept $b$ of the regression line
- Correlation coefficient $r$
- Coefficient of determination $r^2$

- Regression
- Getting started
- Typing your data in the table
- Computing the linear regression
- Displaying statistical variables
- Using the Data tab
- Delete a value from the data table
- Clearing a column of the table
- Using the Graph tab
- Moving the cursor in the graph window
- Predict a value of X or Y
- Adjusting the display window
- Using the Stats tab