Definition
A random variable notation signifying an input to a process or an Independent Variable/factor involved in a Regression or designed experiment analysis, studied for its effect on a response variable of interest.
Examples
In a cake-baking experiment to improve the texture of the cake, the inputs or 'X' variables are the ingredients used in the recipe, e.g. flour, sugar, eggs, etc. In a designed experiment the levels of these factors can be varied in order to determine their effect on the texture of the cake.
See Also
Random Variable
Y