Volunteerism in Zooniverse does have the same structure as other volunteerism if it is about classifications. Usual a lot of volunteers do classify a small set of subjects. They drop by and try the project until they are bored. This can be one subject, ten subjects or one hundred subjects.
Less common are engaged volunteers that classify regular a few subjects until the end of the project, but this would be a desirable classification rate for a base of a few hundred volunteers that classify 10 images per day. This way every project would be done in some months or a year. But in reality the volunteers act after their desires and not after this logic.
A good part of every project is done by a few volunteers that have a lot of time and classify a lot (like myself). This can be used to make the classifications more useful sometimes, because they are “experts”. Same goes for the “regulars”.
Because most of the volunteers only classify if they want to, the classifications start with the launch at a high rate as “everyone” tries the project. In smaller project or in projects with a large support this high rate can be enough to classify all subjects. A launch can be announced by the dailyzoo (news-website of zooniverse), it appears at the project site of Zooniverse and there is usually an advertisement from supporting institutions. The more popular the theme is the more support it gets from other media.
The launch day/week is usually the peak of every project. Everyone does try the project and the second day/week a lot volunteers drop out of the project, but a lot new volunteers try for their first time. The number of new volunteers is lower than the droop-outs. This continues until it reaches a minimum.
Here are the classifications from the “Milky Way Project” phase 3 in weeks. The project aims to do more than two million classifications.
You can see that the launch is clearly the largest peak and after this the classifications decrease. But there appears one small peak. It appears in the week after the launch of Gravity Spy, a Zooniverse astronomy project that classifies “Glitches” from the gravitational wave interferometer LIGO.
This positive effect does appear for launches of astronomy projects. The volunteers who try the new project eventually get bored and try another old project “inside their field”.
A very positive effect was the launch of “backyard worlds: planet 9”, a project that uses WISE data to search for brown dwarfs and planet nine.
It increases form more than 15,000 in the week before the launch, to more than 25,000 in the week of the launch, to more than 35,000 in the week after the launch.
The backyard worlds project had a lot of advertisement and some of the volunteers did also try the “Milky Way Project” after they got bored with backyard worlds. This does have the effect that the classifications gradually increase, instead of a peak on the beginning, like the launch.
After the launch of backyard worlds there are a lot of other important events, like a “Deep Astronomy Coffee Hangout” on youtube where people were able to interact in a live steam via chat and twitter with the researchers. Together with the launch of two other astronomy projects this is a plateau of higher classifications. After the Stargazing live event the classifications decrease like we are used from the launch of the MWP.
A clear peak appears in the middle when the researchers did send a “Help me!” E-mail to the volunteers. This is common for long projects that run low on classifications or that have a new set of subjects. It is very effective at the beginning, but it wears off fast with a similar dynamic like the launch.
Three other projects, Hubble: Hot Stars, Planet 4: Ridges and Supernova Sighting cannot be set into relation to the Milky Way Project.
For the Milky Way Project a desired classification rate of 4000-5000 classifications per day is not the real minimum of the Milky Way Project with about 1000-1500 classifications per day as a current minimum.
One possible origin is the difficulty of the project. A classification can require the parts:
- Is there something?
- What is it?
- Where is it?
- What is the shape of it?
The Milky Way Project does require all those parts while other projects do require only some parts. Beginners do often struggle with at least one part and this insecure feeling is a wall to becoming a regular or expert, which would increase the minimum classification rate.