function isProbability( value ) {
	return (
		isNumber( value ) &&
		value.valueOf() >= 0.0 &&
		value.valueOf() <= 1.0
	);
}
Tests if a value is a number object having a value which is a probability.

@param {*} value - value to test
@returns {boolean} boolean indicating if a value is a number object having a value which is a probability

@example
var bool = isProbability( 0.5 );
// returns false

@example
var bool = isProbability( new Number( 0.5 ) );
// returns true