User blog comment:BunsenH/Ghazt Stats Phase 2, Report 3/@comment-30460778-20161109115824/@comment-24577221-20190825163559

It's possible that the rules have changed, so that monster level and/or happiness may make a difference now. Our reasearch was done several years ago, with a version of the game that had not been updated for a couple of years before that. The Windows version of the game never had the Rare monsters.

But it's important to remember that it takes a lot of tries to get accurate results. The chance of getting a Ghazt is small, so even if you have 10 torches going, it takes hundreds of tries to get the uncertainty down to a couple of percent.