Hi, I am looking for some sample measurement data of devices like Volt, Current, Power and Energy meters. I want to obtain statistical information like variance and standard deviation of data.

Can anyone point me to some good data sources? I couldn't find any after googling for about 20 minutes :p

Some of that data would come from the equipment manufacturer. Some high end devices should have better tolerance but you need a standard to measure against. Check "robotroom.com/multimeter". Torque wrenches have a mil spec of +/- 4%. Google "milspec tolerances", you might find some info there.