The survey research world is still trying to get a handle on how to deal with surveys on mobile devices. Improvements are being made but time and time again I am seeing instances where the mobile experience is being ignored.
While the slider looks decent on the device, as a survey response mechanism, it is unclear what the values are along the slider.
The number on the slider changes as you move, but what if I had five 6-12 year olds?
Things get worse when you actually try and use it. Smartphones are largely driven by the thumb and unfortunately it obscures much of the screen real estate. The second image depicts what the thumb area would hide. As a result the scale and slider is rendered useless.
Ultimately, if direct response surveys are to make the transition to the mobile world, survey designers need to take careful attention to the user experience.