Are there any accurate pedometers?

Answer 1

The advertisements say...
GPS pedometer uses GPS to measure distance. With a good signal, the distance measurement is typically correct to 1%. It can be used for any outdoor activity involving motion, including cycling. In addition, for walking, it gives an estimated step count.

Traditional pedometers use a shaking motion of the pedometer to measure step count. You get a count for each step, or for other motion that shows you are active. It can be used throughout the day to give a rough measure of how active you are.