I want to learn the statistics package [gretl][1].

My first attempt to do so is to calculate a linear regression model of a set of data:

$$y_i = \alpha + \beta x_i + u_i$$

First I want to create a crossplot of the data and then calculate the variance of the residuals $s^2_u$ and also those of $\alpha$ and $\beta$.

My questions are:

How to get the crossplot, I do not see any option in the menu which says crossplot? Is this possible in gretl?

When I click Summary statistics I think I get the $s^2$ of the data, however is it also possible to get the the variance of the residuals $s^2_u$ and also those of $\alpha$ and $\beta?

Is it also possible to calculate in `gretl` a model without $\alpha$, such as:
$$y_i = \beta x_i + u_i$$

I appreciate your answers!

  [1]: http://gretl.sourceforge.net/gretl_and_R.html