[Nick Cox]

Sorry, I can't answer #15 without some context. It looks like a question already answered previously.

[Maarten Buis]

Is it possible to know the value 1.2 lies in terms of the standard deviation so I can insert a line.

The unit on the x-axis is a standard deviation.

I know the 95th centile lies on the 1.96 standard deviation...

No, you do not. That rule only applies if your variable is normally distributed, which looking at the graph in #1 is clearly not the case. If you want to look at centiles , then you need to look at centiles, not at standard deviations. The two are completely different in your case.

[Dirk Enzmann]

Nick Cox : #14 is an extremely good read -- thanks a lot for this "more than you were expecting"! I assume one day we will be able to read your draft worked out into a full paper.