I'm practicing to see how concisely and informally i can explain my honours thesis topic. Here goes:

People think that they're more likely than average to experience good things, and less likely than average to experience bad things. It's a wide spread bias. We call it 'unrealistic optimism'

It might be partly wishful thinking.

My supervisor showed that people are more optimistic about the possibility of something bad happening, and less optimistic about the possibility of the same thing not happening. The former is scarier, and hence people think more wishfully. We call this, 'the valence effect'

Another guy reckons that people might just rate anything that you ask about as more likely for the average person, because the average person makes you think about a group. And when you think about a group, you sometimes accidentally overestimate things. This is because the size of the group tricks you. It's not your fault, it's a quirk of the human mind. This would also explain 'the valence effect', but has nothing to do with wishful thinking.

My thesis project tests between these two possibilities.

The End

That is the absolute quickest I can do it. And i'm leaving A LOT out.

I think it might need some pictures to explain it better.