Where does AT40 get its stats from?

[andrewnz]

It has never been official exactly how the countdown is compiled. Why is there always a blockage of old songs between 30 and 40 particularly between 35 and 40. Week after week songs drop and once they hit 35 they slow down. Take a look at the chart positions of lil boo thang and murder on the dance floor over the past few weeks. Traditionally in the days of Casey Kasey those were the positions that songs debuted. Instead of new songs which should be debuting low it is a collection of “old” hits. Most number ones seem to exit through no. 40 as well sometimes for more than one week eg flowers stopped at no. 40 for 4 weeks. Also most weeks there are exactly 2 debut songs rarely are there more. And AT40 is exactly 2 weeks behind mediabase. For example Fortnight is no. 1 around the world and it hasn’t even made AT40 yet similarly for Espresso. Too sweet has been no.1 here in New Zealand for 2 weeks yet it only just came in at 31 this week. And finally a song only comes on if it has been featured as a on the verge/breakout at least once that’s how I knew fortnight wouldn’t make it on this week - it hadn’t yet been featured.

[woolebull]

I am not sure how they compile it. I mean, mediabase is the source but I think they take liberties with ranking the weekly show as you mentioned. I remember as far back as 2016 when "Love Yourself" by Bieber held at number 40 for I think four weeks as it was going down the chart, which seems impossible in a world where "spins" are computed in real time.

[Shadoe Fan]

When the show first debuted, it supposedly used spins from affiliate stations and included listener requests. There is no apparent recurrent rule, although they do sometimes purge old songs if necessary.