Nielsen data shows Android still reigns supreme in the land of operating systems, though Apple is owning the hardware manufacturing territory. Photo courtesy of Nielsen

As Android spreads across multiple devices, Google’s operating system continues to dominate on smartphones. A report released Thursday backs that up, showing that Android remains the top smartphone operating system in the United States.

But these numbers miss a key point: Android may be the leading platform on smartphones, but what about all the other iOS-powered devices out there that aren’t iPhones — the iPod Touch and the iPad?

Today’s research report, which was published by Nielsen, claims a 39-percent Android platform market share across the major smartphone manufacturers, while Apple’s iPhone operating system claims a 28 percent stake. The results show data from smartphone purchases occurring during the second quarter of 2011 in the U.S.

But therein lies the huge blind spot in Nielsen’s data measurement: Apple sold over 20 million iPhones over the last quarter, but add iPads and iPod Touch devices to that, and the number bumps up to nearly 37 million iOS devices. In three months.

Technology research firms such as Nielsen regularly publish market share analysis to measure which companies are leading the industry. In mobile, Google and Apple are consistently neck-to-neck in market share reports, but it’s questionable why research firms continue to leave tablets and all-in-one portables like the iPod Touch out of the mobile picture.

Which, considering recent reports, may be a big mistake. For instance, GoGo — an in-flight Wi-Fi service provider that works with Virgin America airlines — told AllThingsDigital that while iPhones make up two thirds of wireless devices connected to its in-flight services, iPod Touch devices account for another 20 percent. That’s even higher than the number of Android devices used to access the network (only 12 percent).

Another tidbit to consider: Despite Android’s platform dominance in the smartphone space, over 80 percent of Wired.com’s mobile traffic comes from iOS-based devices. That includes the iPad, iPod Touch and the iPhone. The iPad and iPod Touch aren’t smartphones, but they run the same operating system as the iPhone.

It highlights a specific problem in surveys like Nielsen’s: Measurement criterion. If we’re measuring a platform’s total market share, homing in on “smartphones” specifically rather than mobile devices gives a skewed representation of total platform penetration. It would be a fairer analysis to count all the tablets,smartphones, and all-in-one portables (i.e., the iPod Touch) powered by Android and iOS and comparing those side by side.

Jim Dalrymple of The Loop gives an apt analogy on the matter in an April blog post:

That would be like comparing one model of Mercedes against all cars that GM makes and saying the Mercedes is losing. It just doesn’t make any sense. You can’t have it both ways. You either have to compare hardware devices or operating systems, you can’t mix and match.

A Nielsen spokesman acquiesced when we made the point mentioned above, but countered with an emphasis on how smartphones are one of the more important metrics to watch.

“Smartphones are really driving a lot of the innovation around the different platforms right now,” Nielsen spokesman Don Kellogg said in an interview. “When you look at the smartphone manufacturer share, it’s still very small compared to Apple or even RIM.”

That point highlights the other very important part of the survey. While Android may or may not reign in the smartphone realm, Apple leads the pack as the top smartphone manufacturer with its 28-percent share. RIM, which also owns both its software and hardware, is second in command with 20 percent. HTC also accounts for 20 percent of the hardware market, when taking into account both its Android phone and its Microsoft OS-powered devices.

Which are numbers that may ultimately matter more than platform penetration.

“These things matter from the perspective of securing the deepest level of customer loyalty,” Forrester analyst Charles Golvin told Wired.com. “Because of their vertical integration Apple gets both loyalty components and cements a deeper customer relationship as a result.”