There is no significant drop for 40 where 34 and 44 both do have these. Is this because 40 is pronounced differently and doesn't have the connotation?
Compare 39 to 40, and 49 to 50... I think it's just harder for people to avoid ALL floors starting with 4, but there is still a small effect.
Very interesting work! Just a quick note, for this kind of evenly spaced, discrete X data, stairs plots are usually better. For instance this highlights better the 13th floor issue, which in the line plot was obscured: https://i.imgur.com/cSjT5xx.png
As an R aficionado, I totally agree, but it's not available on Metabase yet, which is the front-end I want to offer non-technical clients to visualise data. I should put in a PR...
I agree that a stepped line graph is better that a line graph, but since the data is discrete and not continuous a lollipop chart or maybe a bar chart would convey it better.
Also a good option, although they seem a bit "busy" for my taste when Y values are very close: https://i.imgur.com/4ePNXbp.png
Its unclear whether the amount of transactions is compensated for the floors that do not exist (thus less supply).
But before that I include a graph of flats available, and indeed there are fewer flats with floor numbers ending with 4! So an interesting analysis would be to see if the turnover (transactions divided by availability) is different... But I think price paid is more interesting :)
Nice work! Do you see any differences when slicing the city into its various districts?