I made some SEDE queries for new question activity, new answer activity, and new user creations per month from 2018 to now (2018 chosen somewhat arbitrarily- I just wanted some more context than looking at just 2022-2023). I'll link to queries for stats on a per-site (using Stack Overflow as the default since it's the biggest site in the Stack Exchange network) and network-wide basis. Thanks to @AwesomePoodles for their cross-site SEDE query template.
Note that you should ignore the recent-most data points in the graphs (/ the sharp dropoffs in the below screenshots for the most recent data point), since they're for the current month, which isn't over yet, and hence doesn't have complete data. I was just too lazy to adjust the query to omit those data points.
New Question Activity Dropped
Per-site: https://data.stackexchange.com/stackoverflow/query/1717975/new-question-activity-per-month-since-2018#graph
Network-wide: https://data.stackexchange.com/meta.stackexchange/query/1717977/network-wide-new-questions-per-month-since-2018#graph
There's usually a sharp drop in activity in December. It was quite pronounced in 2018 and 2019, but not so much in 2020 and 2021. It was quite pronounced in 2022, so it's hard to tell to what degree this is just the normal drop in activity due to time off work and winter break, and to what degree this is from people going to ask their questions to ChatGPT instead of on Stack Exchange.
However, in recent past years, there has always been a pick-up of activity levels in Januaries (observable for 2018-2022), but not so for Jan 2023: The level of new question activity is pretty much the same as the December 2022 level. Interpret that how you will.
New Answers
This graph compares non-deleted and deleted new answer activity per-site:
https://data.stackexchange.com/stackoverflow/query/1717973/new-answers-per-month-since-2018#graph
Though the drop in answers is proportional to drop in questions.
Answer activity in general on Stack Overflow has been in decline since mid-2020.
Similar observations as were made for new questions also apply here. The decline between November 2022 and December 2022 for non-deleted questions was 11.0%. Notice the never-seen-before increase in deleted answer posts from November 2022 to December 2022.
New User Registration Activity Dropped
Per-site: https://data.stackexchange.com/stackoverflow/query/1717972/new-users-per-month-since-2018#graph
Network-wide: https://data.stackexchange.com/meta.stackexchange/query/1717979/network-wide-new-users-per-month-since-2018#graph
- In 2018, there was a 13.1% dip in new users in December, and a recovery in the following January.
- In 2019, there was a 7.6% increase from November to December, and a further 8.0% increase in the following January.
- In 2020, there was little change going into December, and a 9.1% increase in the following January.
- In 2021, there was a 6.1% drop in December, and a 15.4% recovery in the following January
- In 2022, there was a 5.8% drop in December, and a further 12.9% drop in the following January.
Conclusions
Observations: There was no recovery of new question activity and a further drop in new user registrations in January 2023 following December 2022, both of which are declines compared to trends from previous years.
Possible contributing factors:
People are using ChatGPT instead of Stack Exchange. This is likely a significant contributing factor. I've been looking at things people say about Stack Exchange on Reddit and there are plenty of recent comments of people saying that they've been trying to use ChatGPT instead of Stack Overflow, and suggesting that others do the same. (Granted, those tend to be low-score compared to other comments talking about the problems with ChatGPT)
People who use ChatGPT to write answers on sites where it's banned (such as Stack Overflow) are getting suspended, and therefore cannot ask or answer questions.
Activity drops coincide with major tech layoffs in January 2023 and following months. I don't think it's possible to rule out as a contributing factor, especially with most of the largest sites in the Stack Exchange network being tech-related.
More queries and updates / follow-up
I've done further related analyses in my answer post to GPT on the platform: Data, actions, and outcomes. I'm keeping tabs on all my SEDE queries, and I've noticed that the dramatic declines seem to have stopped in the recent months and have stabilized, with some looking like they are about to take recovery paths.
Related Discussions
(Both of which I have written answers for)
And for more general discussion unrelated to LLMs and ChatGPT: Why is traffic on some of SE sites stagnant or in decline, and what is the destiny of such sites?.