When you're declaring variables in a script outside of a function, this distinction is pretty much irrelevant. When you're declaring a variable inside a function and do not use var this creates a ...

A random variable is one whose value is unknown or a function that assigns values to each of an experiment’s outcomes. A random variable can be discrete or continuous.

That's pretty much the right way. Though I'd recommend you function it and put the function in your start script. Here's a working example: ...