I previously looked into the Top 100 Paid apps (henceforth known as the top-sellers) and found that their average price has been declining. In this post, I’ll examine which iTunes categories† are producing the most top-sellers. In terms of number of unique apps, all the categories have grown rapidly over the last two months, with Sports, Education, and Entertainment posting the highest growth rate.
In the absence of download information, the popularity rankings are the best available proxy for “sales”: frequent appearances on the Top 100 Paid Apps list is a good indicator that an app is selling well. Having access to data from around the launch date of the iTunes store, I was able to focus on apps with longer track records (at least 60 days old). The number of days an app spends on the Top 100 list varies across categories:
Of the categories that produce top-sellers, Music was particularly impressive. On average, the 15 Music top-sellers analyzed were on the Top 100 list on 30 different days. (The one Weather app appeared in the Top 100 on 58 different days.) I used duration to see which categories had more proven top-sellers. Solid top-sellers have appeared on the Top 100 Paid apps list on at least 20 different days, while Marginal top-sellers have appeared in less than 10. The Marginal top-sellers have a short-term burst in sales, and are hits for only a few days.
Some categories tend to produce Solid top-sellers (e.g. Music), others produce mostly Marginal ones (e.g. Productivity).
Besides overall sales, Solid and Marginal top-sellers differ in terms of sales velocity (number of days it takes to land on the Top 100 Paid Apps list). On average, a Solid top-seller appears on the Top 100 list the day it launches. It takes a typical Marginal top-seller 5 days to achieve the same milestone. So if an app lands on the Top 100 list quickly, it’s also more likely to appear on the list frequently.
With an estimated 7.5 downloaded apps per device, iPhone users are happily experimenting and searching for useful software. While the Top 100 list is a convenient shortcut, savvier users in search of apps do so within categories. Someone in need of a mortgage app will need to navigate within the Finance category. As this short list of top-sellers illustrates, the Top 100 list is a bit like the Billboard Hot 100: it’s heavy on the pop side.
(†) While apps can be listed in more than one category, the vast majority (≈ 97%) are listed in only one.