  The increasing prevalence of location-sharing features on social media has
enabled researchers to ground computational social science research using
geolocated data, affording opportunities to study human mobility, the impact of
real-world events, and more. This paper analyzes what crucially separates posts
with geotags from those without. We find that users who share location are not
representative of the social media user population at large, jeopardizing the
generalizability of research that uses only geolocated data.We consider three
aspects: affect -- sentiment and emotions, content -- textual and non-textual,
and audience engagement. By comparing a dataset of 1.3 million geotagged tweets
with a random dataset of the same size, we show that geotagged posts on Twitter
exhibit significantly more positivity, are often about joyous and special
events such as weddings or graduations, convey more collectivism rather than
individualism, and contain more additional features such as hashtags or objects
in images, but at the same time generate substantially less engagement. These
findings suggest there exist significant differences in the messages conveyed
in geotagged posts. Our research carries important implications for future
research utilizing geolocation social media data.
