[Redway]

Originally Posted by Joseline

Actually I agree, plus the size of the confidence interval is probably a lot larger for extreme scores.

Yeah, extreme cases tend to be pulled back towards the average. So if you get a very low score (70-), they'll add a lot of points and if you get a very high score (120/130+), they tend to subtract a lot of points.

It's entirely symmetrical for average scores based around 100, so it's a bit uneven before and after that. Particularly in the event of extreme cases, as you say.