First of all, thanks to Hollywood and rpxlpx for your input. I do have a clamp on ammeter that I will use as suggested to see the results. Nearly all of our readings have been actual vs estimated. And those that are estimated have been in line with other billing months.
My suspicion is that the problem may be in the thermostats. I had already replaced the most likely candidates with electronic, auto-sensing thermostats two years ago. They have made no difference in resolving my problem. I live in south central PA where the winters are not overly severe and the summers not all that hot. I am in a heavily treed lot which helps use in the summer to keep our cooling costs down. In the winter we make an effort to keep the thermostats turned down to 70 in those areas which we use most. In those other areas we set them at 65. At night they are set even lower. Often we wear sweaters and cover with blankets in the evening just to stay comfortable and yet our electric bill seems higher than it should be. I have a timer on a five year old, high efficiency water heater and extra insulation.
Short of replacing the heaters we√ïve made several adjustments to try to be more efficient and yet be comfortable. At this point, I think it comes down to replacing all heaters and thermostats or to test the units to replace any defective units. Thus my initial question. I don√ït have a lot of money to throw at the problem, so I want to try to resolve it myself. If I can√ït, then I√ïd like to determine whether it would be economically wise in the long run to spend $6k to get a heat pump system installed or replace all the heaters and thermostats with newer, more efficient units. I√ïve not followed the technological advances of baseboard electric heating to know enough whether I should consider a change. And who do I trust, the electric company or the heating contractors?