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posted by martyb on Sunday July 02 2017, @05:45PM   Printer-friendly
from the dicey-analysis dept.

Passengers have more chance of winning the National Lottery jackpot than being allocated middle seats at random on a Ryanair flight, according to new Oxford University analysis.

In recent weeks Ryanair have faced mounting customer criticism, with some accusing the airline of splitting up groups and families, who do not pay an additional charge for reserved seating. These claims have been rejected by the airline which says that customers who do not wish to pay for their preferred seat are randomly allocated one, free of charge.

Last night, the BBC Consumer affairs programme, Watchdog, ran its own investigation to test how random the airline's seating algorithm is.

As part of their tests, groups of four people were sent on four separate Ryanair flights. In each instance every single person was allocated a middle seat. Dr Jennifer Rogers, Director of the new Oxford University Statistical Consultancy was then invited to analyse the data, to work-out the chances of every person getting a middle seat allocated randomly.

By looking at the amount of window, aisle and middle seating available on each flight, at the time of check-in, Dr Rogers, calculated the chances of all four people being randomly given middle seats on each of the flights, to be around 1:540,000,000. The chances of winning the National Lottery jackpot are 1:45,000,000. (This means that you are 10 times more likely to win the lottery than be in a group who are all randomly allocated middle seats.)

Source: Oxford University


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  • (Score: 2) by wisnoskij on Monday July 03 2017, @02:19PM (5 children)

    by wisnoskij (5149) <reversethis-{moc ... ksonsiwnohtanoj}> on Monday July 03 2017, @02:19PM (#534429)

    Dr Rogers, calculated the chances of all four people being randomly given middle seats on each of the flights, to be around 1:540,000,000

    OK, lets look at this. OK, so some "Dr." runs an experiment with 4 trials, claims 99.999999999999999999999999999999999999999999999999999999999999999% confidence.

    Lets look at the math ourselves.

    Depending on the seating arrangement we most likely get 1/3rd of the seats being middle seats. It is possible for none of the seats to be middle seats, it is possible half the seats are middle seats. But 1/3rd is very common and it appears to be what Ryanair uses.

    So grade 9 statistics give us.

    Four independent events, assuming that we start with airline with 0 reserved seats (or reserved seats that were uniformly reserved across aisle , window, and middle)
    1/3 * 1/3 * 1/3 * 1/3
    = (1/3)^4
    = 1/81
    Or a 1:81 chance. A 7 million percent difference from what Rogers found.

    Now lets look at how confident we are at this answer.

    Standard Deviation = sqrt(sum(difference from mean)^2/num_trials)
    = sqrt((((2/3) squared) * 3)/4)
    = 0.58
    This is also pretty close to what we get for our confidence interval with a 95% confidence level

    OK, that is pretty horrible, so we found that the chance of randomly being assigned a window seat is 1 +or- .6

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  • (Score: 2) by wisnoskij on Monday July 03 2017, @02:25PM

    by wisnoskij (5149) <reversethis-{moc ... ksonsiwnohtanoj}> on Monday July 03 2017, @02:25PM (#534433)

    * Middle Seat

  • (Score: 1) by chair on Monday July 03 2017, @03:56PM (1 child)

    by chair (6194) on Monday July 03 2017, @03:56PM (#534467)
    from the (very short) FA:

    To support her analysis, Dr Rogers was also given access to data from a further 26 individuals, from nine groups, who had been separated from their party when travelling with Ryanair.

    • (Score: 2) by maxwell demon on Monday July 03 2017, @04:18PM

      by maxwell demon (1608) on Monday July 03 2017, @04:18PM (#534472) Journal

      To support her analysis, Dr Rogers was also given access to data from a further 26 individuals, from nine groups, who had been separated from their party when travelling with Ryanair.

      Sounds very much like biased data sampling.

      --
      The Tao of math: The numbers you can count are not the real numbers.
  • (Score: 2) by FatPhil on Monday July 03 2017, @04:19PM (1 child)

    by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Monday July 03 2017, @04:19PM (#534474) Homepage
    There aren't 4 events, there are 16 events.

    Which implies, all things being equal, a probability of .28 of getting a middle seat for the Doctor's calculation. Which seems to imply many pairs making adjacent seat reservations, and thus snarfing middle seats making them rarer than the no-assumption 1/3 /a priori/ probability.
    --
    Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
    • (Score: 2) by wisnoskij on Monday July 03 2017, @08:08PM

      by wisnoskij (5149) <reversethis-{moc ... ksonsiwnohtanoj}> on Monday July 03 2017, @08:08PM (#534557)

      Ah, I missed that. That still only gives you a 50 million to 1 probability. Another sentence I missed "By looking at the amount of window, aisle and middle seating available on each flight, at the time of check-in" might imply that many of the middle seats were already taken, presumably by already checked in not paying extra customers.

      Basically, if you want an aisle or window seat, check in late.