Up until now, using the previous dashboard’s available data, a Tweet’s impact was measured largely by the number of Retweets and favorites it received. That data will still be visible in the new dashboard — available to verified users, Twitter Card publishers and advertisers — along with additional details into the various ways people are engaging with your Tweets and new insight into the reach of your Tweets with impressions data.
This impressions metric tells you how many times your Tweet has been viewed on Twitter’s Android and iOS apps or on Twitter.com. You can view the total impressions on a Tweet, as well as an hour-by-hour breakdown for the first day of that Tweet. You also get insight into total impressions for all your Tweets in aggregate over a 28-day period.
In addition to the number of impressions, Retweets and favorites your Tweet received, the dashboard gives a breakdown of how people are engaging with it. Just click on the Tweet you’re interested in and it will expand to show you more detail. For Tweets with links, for example, you’ll see link clicks; for Tweets with hashtags, you’ll see hashtag clicks; for Tweets with App Cards, you’ll see how many times people clicked to install your app or open it (if it’s already downloaded). And if you receive follows or profile views from a particular Tweet, you’ll see that too.
Finally, in addition to a web interface refresh for all Tweet activity the CSV export tool will show you data for up to 3,200 Tweets (up from 500) and includes a breakdown of all impressions and other engagement numbers.
Source: twitter blog