Passing Var Valuable To SetTimeout Not Working?

I hav a setTimeout at the tail end of a function. On time out I am running a function and passing argument values but they do not seem to be passing to the setTimeout.

For example (snippet from full code to save you time)

Code:

var billboard_number_new = 3;
setTimeout("rw_billboard_num_chooser(billboard_number_new)", 5000 );

Even if I test with an alert it still will not acknowledge the value of billboard_number_new

Code:

var billboard_number_new = 3;
setTimeout("alert(billboard_number_new)", 5000 );