Three Apps or dashboards created with R package Shiny. It takes a few moments to activate the Apps in the server as they are stopped after 10 min without user interaction.

*At the moment I have a free account of the hosting service. If the free quota is used up and the Apps stop working, please contact me, and I will buy additional computing time.*

*t*-distribution compared to the Normal distribution

As the number of degrees of freedom increases the *t* distribution approaches the Normal distribution.

The observed *t*-value is calculated as \({\bar x} / s_{\bar x}\), or more generaly the estimate of the value of a parameter divided by its standard deviation.

*F*-distribution

The observed *F*-value is the ratio between two estimates of variance \(s^2_1 / s^2_2\). If the variance as numerator is larger than the denominator \(F > 1\). The degrees of freedom of the two variances determine the shape of the distribution.

If we know the observed *F*-value, and degrees of freedom we can look up the *P*-value from the theoretical distribution.