Mat Piscatella of the NPD group has just shared that the PS4 is the third fastest-selling console in the U.S., behind the Wii and PS2. Piscatella described the data as time aligned, which means that it ?compares products over the same number of months for sale. [It] makes for more fair comparisons across products.? This means that the PS4 is measuring its first 68 months against the first 68 months of each of the other consoles it is being compared to.
You can find Piscatella?s tweet below:

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