Google’s Android operating system continues to dominate the smartphone market in the U.S, according to market research firm Nielsen.

The latest Nielsen statistics released on Thursday showed that Google-run OS leads the U.S. smartphone market with 39 percent of the market share in June compared to just 28 percent for Apple iOS. Meanwhile Research In Motion’s Blackberry OS continued to decline in the smartphone platform market and brought up third place with 20 percent.

Is Android really leading the market?

This is the biggest question as the survey didn’t consider the other iOS-powered devices iPod Touch and the iPad.

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, according to Wired.com.

Meanwhile, in a TechCrunch story Tuesday, it was reported that Android's activation numbers may be misleading.

During Google's earnings call on July 14, it was revealed that 550,000 android devices were being activated every day. However, the article states that 30 to 40 percent of all activated android devices are being returned.

When accounted for, that would mean that really only 330,000 to 385,000 devices are truly being activated each day. With Apple selling 33 million iOS devices in the last quarter, that would put them at around 366,000 iOS device activations a day.

Even when subtracting the 1 percent of returns that Apple says it gets on iOS devices, Apple would still be activating 362,000 iOS devices a day.

Steve Jobs has criticized Google on multiple occasions for counting upgrades as activations, implying that Google was in some way cooking up the numbers.

However, the iPhone remains the most popular phone because the Android OS runs on many diverse devices HTC, Motorola and Samsung.

If the Android phones were divided by the manufacturers, Apple remains the top smartphone maker in the United States with 28 percent market share. HTC would follow with 20 percent market share including 14 percent of Android phones and 6 percent of Windows Mobile/Windows Phone 7 gadgets. After that, Motorola has 11 percent and Samsung has 10 percent.

Therefore, all HTC Android phones have less than 15 percent market share, all Motorola Android phones less than 11 percent, and all Samsung Android phones less than 8 percent.

Moreover the iPhone is the more adored smartphone as the iPhone 4's return rate is just 1.7 percent compared to the return rate on certain Android devices is as high 30 to 40 percent.

In addition, a recent ChangeWave Research poll revealed that 70 percent of Apple iOS customers are "very satisfied" with their product. This compares to 50 percent for Android and just 26 percent for RIM.

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