Android devices (including Fire Phone, which uses a forked version of Android) do under-index - though not much.
(BlackBerry devices under-index on Chitika, making up 0.5% of browsing, but having 2.4% of the installed base).
But what if Fire Phones "under-index" on Chitika's system - that is, they don't show up on its ad networks as much as other devices, because their users are (for example) all spending time on Amazon buying things, rather than browsing the parts of the web that Chitika supplies ads for?
On that basis, you could argue that if the Amazon Fire Phone under-indexes, it probably isn't by much; you could multiply the number by 25%, based on the average of the Samsung and HTC figures.
To explain "under-indexing", imagine there are 100 owners of device A, and 100 owners of device B, and 100 of device C. If owners of A and C use their devices online an equal amount of time, but device B owners spend only half their time online, a system that measures web impressions will report that there are half as many owners of device B. One would say that device B "under-indexes".
"Given the popularity of game apps you might expect that Millennials drive that usage," explains Khalaf, "but in fact they under-index for game app usage.
Probably the biggest finding is that this group under-indexes on mobile games, as compared with the rest of the mobile population.
Women under-index in the top ranks.
The statistical significance between the areas under indices receiver operating characteristic curves was calculated by the DeLong method.
For math competence the average Capability Under-Utilisation Index was rather neutral with MCUUI-Math = -0.001 (SD = 0.02).
Figure 3 The relation between math-science coherence and the capability under-utilisation index for science and problem solving scores across the 41 countries.
