Assume a given variable, $x$, has a value that is a function of a set of variables, $a, b, c$.
$a, b,$ and $c$ can be said to be the independent variables. However often times in modelling real life scenarios, $a, b,$ and $c$ will have values dependent on another "layer" of variables, and those variables will be dependent on yet another deeper layer.
In the context of this perspective, is there any proper or common term used for these variables instead of "dependent" and "independent", that does more to denote the hierarchical nature of this chain of variable dependencies?
For lack of a better term i have just been saying "subvariables" but would like to know if I am missing a better term.