I) Establishing Key Formulas
D) The Finishing
The market evolves year after year, but it also evolves week after week. While for most of them the differences are small and fall into the averages there is an exception. The big gap comes when the holiday season kicks in. Sales explode and do not fit anymore within the scale we defined earlier.
To fix this situation, we have to insert the Christmas factor. The higher an album is charting in December, the highest the factor must be. Inside the formula that we will conclude on, I added a column in which it is hardly needed to put the same scale weight – for example 2 for #100 – as per the ranking the album occupies at Christmas. If this appears to be unclear, the various examples we will expose later on will clarify it.
The finishing also includes slight manual adjustments for specific cases. For example, if an album charts 2-2-2-2-2-2-5-8-11 while another ranks 5-5-5-5-5-5-5-8-11, both albums will have the same result since the 2 and 5 positions are grouped together. Naturally, the album peaking at #2 sold more, especially if it was blocked by a huge #1 LP. When those occurrences of an album riding close to the boundaries of a group for very long happen, weeks may be split equally between the highest and the lowest group. Thus, 2-2-2-2-2-2- is similar to 1-1-1-2-2-2- sales-wise while 5-5-5-5-5-5- is closer to 5-5-5-6-6-6-.
The same occurrence can happen on lower parts of the charts, but the difference between #100 and #101 is very small so doing those adjustments is a waste of time.