function incrmmeanabs2( W ) {
	var mean;
	if ( !isPositiveInteger( W ) ) {
		throw new TypeError( format( 'invalid argument. Must provide a positive integer. Value: `%s`.', W ) );
	}
	mean = incrmmean( W );
	return accumulator;

	/**
	* If provided a value, the accumulator function returns an updated mean. If not provided a value, the accumulator function returns the current mean.
	*
	* @private
	* @param {number} [x] - input value
	* @returns {(number|null)} mean or null
	*/
	function accumulator( x ) {
		if ( arguments.length === 0 ) {
			return mean();
		}
		return mean( x*x );
	}
}
Returns an accumulator function which incrementally computes a moving arithmetic mean of squared absolute values.

@param {PositiveInteger} W - window size
@throws {TypeError} must provide a positive integer
@returns {Function} accumulator function

@example
var accumulator = incrmmeanabs2( 3 );

var m = accumulator();
// returns null

m = accumulator( 2.0 );
// returns 4.0

m = accumulator( -5.0 );
// returns 14.5

m = accumulator( 3.0 );
// returns ~12.67

m = accumulator( 5.0 );
// returns ~19.67

m = accumulator();
// returns ~19.67