Often when we help plan and host a Twitter Party or Twitter Chat, our clients request that we provide them with an in-depth report of how their hashtag performed during the event. And, more often than not, once the report is sent, we receive questions about what all of the statistics mean and what the differences are between them.

Here’s a quick synopsis of common terms used when tracking a hashtag, what those terms mean and how they were achieved:

REACH Simply put, this term reveals the maximum number of Twitter users your hashtag has reached. Or, the maximum number of users who might have seen your hashtag at least once. For example, if I have 100 followers and I tweet using a specific hashtag once, my reach is 100. If one of those users retweets that tweet just once, and  they too have 100 followers, that tag’s reach is now 200. If I tweet again using that same hashtag, I’m still ‘reaching’ the same users, so my reach stays at 200.

EXPOSURE This term measures the number of impression the hashtag had. This is different from reach in that the data on impressions shows how many times that hashtag showed up in someone’s time line. To expand upon our example above, I tweeted twice to my 100 followers, one of those followers tweeted once; our total reach is 200, but our impressions is 300. That hasthag appeared in a timeline 300 times.

ACTIVITY This gives you the number of individual tweets that were sent using that hashtag. In using the examples above, I tweeted using the hashtag twice; one of my followers once. Those three tweets reached 200 users and had a frequency of 300. But since it only took three tweets to do all that, our activity is just that: three tweets.

CONTRIBUTORS These are the total number of users — regardless of how many tweets they sent — who sent a tweet containing that hashtag. In our hypothetical example, I tweeted using the hashtag twice, and one of my followers retweeted it once. Though three tweets used the tag, only two users sent them. Thus, our statistic for contributors is two users.

The above terms will help you to best judge how many times your hashtag bounced around the Twittersphere. However, whether or not people saw — and better yet absorbed — your message usually can only be judged by the results of your calls to action sent during the party (such as added followers, newsletter sign ups, coupons used, new Facebook fans, etc.).

For more information on tracking hashtags and what service providers to use-as well as how to plan a Twitter Party or Chat-please check out our eBook now available for purchase at http://bit.ly/tweepartiesbook!