Fun With Numbers: Amazon Tracking vs. Sales (12/14-20, 2015)

Another week of holiday-season data, one week before the one with the big day in it. Thankfully, BD and DVD data both updated properly this time, so it’s a very straightforward breakdown.

Raw Data:



(The below plots contain the same data, but on different axes to give a better view of different parts.)

w17-plot_base w17-plot_xcrop w17-plot_ycrop

Formula Recap:

#10k-#40k: S=10-(R-10000)*(9/30000)
#2k-#10k: S=30-(R-2000)*(20/8000)
#1k-#2k: S=70-(R-1000)*(40/1000)
#500-#1k: S=220-(R-500)*(150/500)
#200-#500: S=250-(R-200)*(30/300)
#150-#200: S=800-(R-150)*(550/50)
#100-#150: S=1000-(R-100)*(200/50)
#50-#100: S=1300-(R-50)*(300/50)

Average versus Expected Sales:

So how much did the retail-strong holiday season help out anime sales this time around? I computed “expected” gains using my formula based on non-holiday data and compared those numbers with the ones actually on the official reports, excluding Vampire Hunter D (tracking shot to hell) and the AoT special editions (negligible). In the last column, expected BD values are black, and expected DVD values are grey.


Once again, we see a remarkable level of agreement between the expected level of sales as predicted by amazon ranks and the actual accumulated totals. Out of the 27, the only 3 releases where the expectations and actual values differ by more than a factor of 2 are the DBZ:F BD, Arietty on DVD, and OP:SW on DVD (traditionally an underperformer). A few sets are close enough that it’s almost spooky (OP:FZ and Eva:Ha on BD).

Also, I did a little bit of statistics with these values this week for kicks. Comparing single releases that count as a single entry (i.e. everything on the above list except DBZ:F on DVD), you get that, on average, formula expectations were about 4%±69% below of the reported values. Exclude OP:SW on DVD (a huge outlier overestimated by over 300%), and the expectations are 17%±21% below the actual total. In addition to showing how tight the correlation here is, this does indicate the holiday season is providing a general, if low-level, boost to sales for these volumes.

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