When I was fresh out of college I worked for the local county GOP for the 2004 election as a field rep. Basically, my job was to assist volunteer HQ's in recruiting other volunteers for precinct walks and phone banking for the election.
Most of it was a sham numbers game, and even though I didn't get it back then I understand why now. We were encouraged to essentially exaggerate by counting as a "yes" anyone who said anything other than a hard "no."
At the time I thought that was stupid, but now I understand that a maybe could turn into a yes. Still, if someone says they have 1000 volunteers for something the real number might be 10% of that.
That was a local GOTV effort, what's the difference between that and Obamacare's 7 million sign-up claim? Other than more power and money...nothing.