How google analytics works whether it's based on 24/7 or weekly basis , If the result is correct or approximately.
It works on Javascript ,So whenever you site loads in a browser ,a hit will be recorded in Google's analytics database Google's analytics is not exactly correct,it's more or less approximate...
I've found that it's pretty close. What is really useful is being able to see what keywords and referring sites are bringing traffic to my site.
I've used other stat counters and I find google the best for this, although it isn't perfect it's pretty close. If anything I think it might underestimate visitor numbers
These answers are all speculation. We are making assumptions here. Since Google hasn't told us how accurate it is or isn't we can only guess. My guess is that it is very accurate.
Google Analytics is not as perfect. I compare my stats with cpanel log files, and it is pretty much near. No two analytics tool will show you same results anyways. but i like the interface and details that it provides. Just my 2 cents!