A1,We don't know how Unsw marks interviews, whether by percentages out of 10 or 100 or whatever. But if true to the words they wrote to us the scores will be standardised (same as ATAR & UMAT) so doesn't really matter.
The estimated percentage given in the email is chance of getting a place not interview score. However see my explanation below I think we can *roughly* relate it to the percentile of one's interview score.
IMO you are absolutely spot on. Since Unsw already knows the place cutoff and your ATAR & UMAT, if coupled with max intv score they already can tell whether you are or are not getting a place. It doesn't make sense to say getting the maximum interview score gives you >X% chance.
I kinda think Unsw wrote like that to avoid any legal challenges. The real meaning of that is more like: If Unsw were to put 100 typical intv scores into a bag and draw one out for you, you have >X% chance it combines with your ATAR/UMAT to above the cutoff. Make sense? Thus I approximate it to the percentile of your interview score (i.e. >70% chance means 30%ile+ score).
(Writing this in a hurry, will edit if I can think of better ways to describe).
have a look at my reply earlier.
I don't think that you can link the likelihood to the percentile except by coincidence.
From the info posted what they are saying is.... given
1. your scores for UMAT and ATAR and
2. the distribution of scores that we have seen on interviews
it is x% likely that you interview score will be high enough to get an offer.
I think that this is a classical confidence interval exercise... happy to be corrected by someone that understand stats properly