Q: How to do statistic on action in Facebook Ads I am confused about action concept when calling Ad Statistic with start_time.
For example, make a call like below:
https://graph.facebook.com/act_<account_id>/stats?start_time=<ONE HOUR BEFORE NOW> & access_token=<>

it will return stats data like:
account_id:xxx,
impressions:10000,
clicks:500,
action:{
   mobile_app_install:20
}

Does action number mean action after start_time (as example, one hour before now) or it means all actions in Attribute Window? 
Does start_time have influence on action number returned?
Thanks a lot.

A: Action Number is All actions in the attribute window after the start_time
start_time does affect the action number as the action number can changed based off of what is occurring at different times of the day when the Ad statistic is in use.

A: It's one and a half years later and Facebook API has updated to new versions.
For start_time, it has changed from unix_timestamp to 
"time_range:{'since':YYYY-MM-DD,'until':YYYY-MM-DD}"

There is no way to set hour info inside it, all stats (which called insight now) are at least day-level.
Question1:
Does start_time have influence on action number returned?

Yes, of course, Facebook Insight will return action and other stats between since and until time.
Question2:
Does action number mean action after start_time (as example, one hour before now) or it means all actions in Attribute Window?

Actions will be flagged into the last view or click lead to the install, which decided by setting (28 days view and 1 days click in general). That action will be counted in the time of views or click, instead of the time of install happened, that's why previous data may change after some time later.
