Swiss' results were based on 59 responses, Turkish Airlines on 38, Lufthansa 74 and Aer Lingus 65.
Ryanair's results were based on 563 responses.
This is why the "Which" survey is very seriously flawed. How can you compile a survey with such small groups. 59 is less than one aircraft, 563 is about three aircraft. These would need to be corrected for number of flights/total passenger numbers amongst many many other adjustments and even then it would still be one very poorly compiled survey by people who really do not have a clue about statistics or any other form of data mining,
