[Script Info]
Title:
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:02.00,Default,,0000,0000,0000,,And here is my answer.
Dialogue: 0,0:00:02.00,0:00:06.00,Default,,0000,0000,0000,,There are a number of ways to do this, but a simple one is to take the old mean,
Dialogue: 0,0:00:06.00,0:00:09.00,Default,,0000,0000,0000,,multiply it by the number of observations, which gets us the sum,
Dialogue: 0,0:00:09.00,0:00:13.00,Default,,0000,0000,0000,,add to it the new value, which gets us the new sum,
Dialogue: 0,0:00:13.00,0:00:15.00,Default,,0000,0000,0000,,and then divide it by the new number of observations,
Dialogue: 0,0:00:15.00,0:00:18.00,Default,,0000,0000,0000,,which is just one more than the old one.