I noticed Davids odds of winning drops a lot whenever he is up for evictions, not just this week. This is due to David's honest nature which may put people off. But when ever David not up for eviction, his winning odds increases alot as well.
There are a few times that David and Priya were up for evictions in the same week and the bookies tends to give David a higher odd for eviction over Priya, but each week it is generally David who is most saved over Priya - proving the bookies wrong...
When other housemate are up for evictions their winning odds dont drop as much as David's. This is due to that housemate's predictable nature such as showmance / under the radar.