Finding out when stuff has changed, without re-fetching everything

Hi Everyone,

I'm fairly new to the API, but it's working well for me so far. What 

I’m wondering is, for data sets which can be quite large, e.g. bank
transactions and expenses, is there a way to tell whether there is new data

What I'm trying to do is create a dashboard which will show an 

aggregate amount of expenses per user per category within a given time
period. It would be great if I could get a property somewhere that could
tell me if someone’s expenses had changed, i.e. when was the last time any
expense entries were added / updated / deleted for a specific user.

Also, is it the case that on a bank_account object, the updated time 

field will tell me when the last time any transactions against that account
were changed?

thanks in advance,