He didn't find a correlation, or rather found that there is no correlation, between proximity to a railway station and how the kebab is reviewed. It's a nice study for a statistics class!
There may not be a correlation, but you can clearly see that the bottom-right quadrant of the plot is basically empty, which is an important insight. A more accurate aphorism would be "You can sell good kebabs anywhere, but you can only sell bad kebabs near a train station." And if you look at the "minimum viable quality" instead of the overall quality, there does seem to be a linear correlation with the distance. Yo…
Insightful!
97.38% of bad studies measure the wrong variable.
Do drunk french people buy kebabs? In my city one central late night kebab place has great kebabs. Anecdotally I remember one great kebab cart serving at least one drunken customer in Nice (France) - not near a station and a long way from the Paris metro!
I think there's some population selection flaws. Drunk people don't leave reviews. In foreign countries it is difficult to know the correct search term.
I suggest an alternative study: how much lager does it need to make a train station kebab taste great?