public function getValue() {
		// If we have five samples or fewer, fall back to a naive method.
		if ( $this->getCount() <= 5 ) {
			sort( $this->heights );
			$i = $this->p * count( $this->heights );
			if ( $i === floor( $i ) ) {
				return ( $this->heights[$i - 1] + $this->heights[$i] ) / 2;
			} else {
				return $this->heights[floor( $i )];
			}
		}

		return $this->heights[2];
	}