Is Twitter in Australia becoming less angry over time?

A couple of days ago, I posted about Donald Trump's lack of sleep and his performance as president. One of the findings of the research I posted about was that Trump's speeches and interviews were angrier after a night where he got less sleep. However, if you're like me, you associate Twitter with the angry side of social media, so late-night Twitter activity would seem likely to make anyone angry, sleep deprivation or not.

One other thing that seems to make people angry is the weather, particularly hot weather. So, it seems kind of natural that sooner or later some researchers would look at the links between weather and anger on social media. Which is what this recent article by Heather Stevens, Petra Graham, Paul Beggs (all Macquarie University), and Ivan Hanigan (University of Sydney), published in the journal Environment and Behavior (sorry, I don't see an ungated version, but there is a summary available on The Conversation), does.

Stevens et al. looked at data on emotions coded from Twitter, average daily temperature, and assault rates, for New South Wales for the calendar years 2015 to 2017. They found that:

...assaults and angry tweets had opposing seasonal trends whereby as temperatures increased so too did assaults, while angry tweets decreased. While angry tweet counts were a significant predictor of assaults and improved the assault and temperature model, the association was negative.

In other words, there were more assaults in hot weather, but angry tweets were more prevalent in cold weather. And surprisingly, angry tweets were associated with lower rates of assault. Perhaps assault and angry Twitter use are substitutes? As Stevens et al. note in their discussion:

It is possible that Twitter users are able to vent their frustrations and hence then be less inclined to commit assault.

Of course, this is all correlation and so there may be any number of things going on here. However, the main thing that struck me in the article was this figure, which shows the angry tweet count over time:

The time trend in angry tweets is clearly downward sloping (see the blue line) - angry tweeting is decreasing over time on average. Stevens et al. don't really make a note of this or attempt to explain it. You might worry that this is driving their results, since temperatures are increasing slowly over time due to climate change. However, their key results include controls for time trends. Besides, you can see that there is a seasonal trend to the angry tweeting data around the blue linear trend line.

I wonder - is this a general trend, or is there something special about Australia, where Twitter is becoming more hospitable? The mainstream media seems to suggest that Twitter is getting angrier over time, not less angry. Or, is this simply an artefact of the data, which should lead us to question the overall results of the Stevens et al. paper? You can play with the WeFeel Twitter emotion data yourself here, as well as downloading tables. It clearly looks like anger is decreasing over time, but it may be a result of changing trends in the use of Twitter (or who is using Twitter) over time, especially in the change of language use over time.

I would want to see some additional analysis on other samples, and using other methods of scoring the emotional content of Twitter activity, before I conclude that Twitter is angrier when it is colder, or that Twitter anger is negatively associated with assault. On the plus side, the WeFeel data looks like something that may be worth exploring further in other research settings, if it can be shown to be robust.