" On the contrary, the D3200 shows significant low-light improvement over the D3100 (with its 12 Mpix CMOS sensor), which had achieved a DxOMark low-light score of 919 ISO."
Nikon D3100 does not have a 12 Mpix sensor but a 14.2 Mpix sensor:
http://www.europe-nikon.com/en_GB/product/digital-cameras/slr/consumer/d3100Interesting to see that D3200 and D3X score so high. They both are only mediocre in high sensitivities compared to, for example D5100 & D7000. Maybe in the end the megapixels count...