Keywords: attach rate, measure of popularity, complementary goods
The attach rate of a product represents how many complementary goods are sold for each primary product. For example, the average number of DVD-Video discs (complementary product) purchased for each DVD player (primary product) sold, or the number of console-specific video games purchased for each console sold.
The attach rate is one measure of popularity for a given platform, since it is an indication of how quickly sales for the complementary products will grow as the installed base of the platform grows.
For example, imagine the following situation:
- Platform A has sold 1,000 hardware units
- Platform B has sold 10,000 hardware units
- Publishers have sold 5,000 titles for Platform A
- Publishers have sold 10,000 titles for Platform B
In absolute terms, Platform B is outselling Platform A by a factor of 10:1, but Platform A has a much higher attach rate (5:1 versus 1:1). Thus for a content provider, Platform A may be more attractive, since at current attach rates the platform only needs to sell another 1,000 units for publishers to match their sales on Platform B.
Nevertheless, the attach rate can be skewed early on in a product's life-cycle due to the effect of early adopters whose consumer behavior may not be representative of the general populace. Attach rates also fail when considering a product late in its life-cycle. Using the DVD player example above, the adoption of the DVD-ROM format in computers and software would have a dramatically negative effect when the complementary product is DVD movies because many of these multi-use devices rarely are used to play videos.
