Shell Gas and Your Z

Originally Posted by Jordo!

Hmm. If true, that makes me wonder whether or not there is more variance in actual octane per company.

The advertised octane is an average... could be there is more variance for some companies, meaning a greater likelihood you'll get a slightly lower (or higher) octane fuel.

The skeptic in me wants to ignore this, but the statistician in me realizes that mean values (and the associated distribution of scores) are harder to interpret without knowing the SD.