Be careful what you tweet -- you may be inadvertently giving away your location.
That's the conclusion of a recent study conducted by a University of South California graduate student. After building an application that analyzed more than 15 million tweets over a one-week period, lead author Chris Weidemann discovered that 20 percent of tweets reveal a Twitter users' location.
"The scary part about Twitter is that it's all publicly available data," Weidemann wrote in an email to The Huffington Post.
Though Twitter automatically includes location data for users who have geo-tagging enabled, Weidemann and his team found that many users who opt out of this setting also reveal specific details about their location -- whether by name-dropping a specific establishment or through metadata in photos.
"Roughly six to eight percent of all tweets include a GPS location," Weidemann told HuffPost, explaining the most common type of location-revealing tweets. "That's upwards of 30 million tweets a day. Beyond that, we've found the most common is physically identifiable text inside a tweet."
As part of his master's thesis for USC's Spatial Sciences Institute graduate program, Weidemann built an app called Twitter2GIS, which is capable of capturing location data from Twitter. The tool then analyzes text and metadata in order to translate it into personal location information.
For example, if a Twitter user mentions a particular restaurant in a tweet, the tool will pull that establishment's address from Google to determine the user's location. If the restaurant mentioned is part of a chain or has several locations, the tool will search past tweets in an attempt to narrow down the locale.
In all, Weidemann said the app took about four months to build, since he also works full time as a senior geospatial technology manager for a federal contractor.
Along with a research paper published in the International Journal of Geoinformatics earlier this year, Weidemann also created a webpage that allows Twitter users to check their own accounts. If a user's last 200 tweets included any location data, the tweets will show up as points on a zoomable Google map. The website will eventually pull in all tweets, Weidemann added.
Additionally, the search tool allows at-risk users to download their location-revealing tweets in an spreadsheet document and toggle a heat map feature to see the hotspots (in red) where they revealed their location the most often. The site also offers explicit suggestions on how to prevent future over-sharing.
"People should be aware that corporations and intelligence groups are using this type of analysis to create user/target profiles," Weidemann said. "I felt that if people were going to be using this against the average Twitter user, someone needed to at least make a tool that allowed a user to view their own risk and manage it."
Do any of your tweets reveal your location?
Check your risk level with the beta version of Weidemann's tool (here) by typing in your Twitter username and clicking "Retrieve Tweets."
If you have given away a bit too much in the past, follow these general tips in order to hide your location on Twitter.
- First, check if you have "Add a location to my Tweets" checked under security and privacy settings. If you do, uncheck that box and save changes. (You may also opt to delete all location information.)
- Be wary of other applications, such as Foursquare, that may have authorization to post to your Twitter account. You can find out which apps you've already authorized under the apps section of Twitter's settings page, and you also have the option to revoke access for individual apps.
- When you take a photo on your smartphone, GPS coordinates are usually embedded in the image's EXIF metadata (unless you disable geo-tagging, or use an app to manipulate this data.) While Facebook and Twitter strip metadata from photos uploaded directly, other sites like Flickr and Twitpic maintain this information, the Electronic Frontier Foundation notes.
- Be cautious when tweeting information that is unique to a specific location. (You're giving it away!)