Atmega328p Power Saving Techniques

kentc:
You know it sleeps properly when you are able to measure the current dissipation across the chip to be less than .1mA. The chip can go as low as .1uA if you set the fuses and clock correctly.

I know that...my question is about how to accurately measure the current. I want to confirm that I'm setting the fuses and clock correctly.

Of course we're going to measure a small current if we put a 1 Megaohm resistor in a 5V circuit, Ohms law tells us it can't possibly be more than 5uA.

I want to know how this method tells us the current consumption of the AVR chip. It doesn't make any sense to me.