移動平均してみた。(±1.5 のデータを25%ずつブレンド：元の値50%)

b-a の分布
---------
-8.0, 0.5,
-7.5, 0,
-7.0, 2.5,
-6.5, 2.5,
-6.0, 3.5,
-5.5, 5,
-5.0, 6.75,
-4.5, 9.25,
-4.0, 11,
-3.5, 14,
-3.0, 16,
-2.5, 20.75,
-2.0, 22,
-1.5, 23.75,
-1.0, 28.75,
-0.5, 29.5,
0.0, 33.5,
0.5, 32,
1.0, 34.25,
1.5, 39.25,
------------
2.0, 33,
2.5, 32.5,
3.0, 32,
3.5, 30.25,
4.0, 27.5,
4.5, 23.5,
5.0, 23.25,
5.5, 19.75,
6.0, 16.5,
6.5, 13,
7.0, 10.5,
7.5, 8.75,
8.0, 5,
8.5, 4.75,
9.0, 3,
9.5, 2,
10.0,2,
10.5, 0,
11.0, 0.5,
----------
計, 624,
標本平均Average, 1.43108975,
標本分散, 11.64829625,
標本標準偏差, 3.41296005,
最頻値mode, 1.5,
中央値median, 1.5