The Bias Study
Happy New Year from Galaxy Zoo! 2007 has already left for some of you, and for others, it will be leaving soon. 2007 has been a great year for the study of galaxies, thanks to the galactic classifications that you have completed. I thought that in today’s post, I’d tell you a little more about what we are doing right now, as 2007 turns to 2008. Chris originally posted about this in the forum, and Kate has been providing a status update.
In last Thursday’s blog post, Chris gave an introduction to projects that the team is now working on. When he talked about Kate and Anze’s cosmology study (finding the rotation directions of spirals), he mentioned that a key to this project was completing the bias study. That “bias study” includes the rotated, mirrored, and black-and-white galaxy images that we’re asking you to classify now.
For those of you that aren’t familiar with what scientists mean by “bias,” it’s one of those funny words that has a specific meaning in science that is different from its meaning in everyday life. When we say “bias” in daily life, we often mean that someone has an agenda that means they can’t be trusted. For example, we might say that a news organization has an [insert political viewpoint] bias that means you just don’t trust that they’re giving you an accurate picture of the news.
That’s not what we mean here, though! There are several related meanings of the word “bias” in science, but they all come down to the question of whether results were influenced by some factor that the scientists didn’t think about. The scientist might ask himself or herself: Did I really study everything I could have studied? Did I do the right type of analysis on the data? Did I have some preconceived idea that kept me from interpreting the data with an open mind?
The question that we are asking is about how people see galaxies. When you see a fuzzy galaxy, is it easier to see it as an anticlockwise spiral than a clockwise spiral?
We’ve talked with some colleagues from psychology, and there is no reason to think that should be the case – but we want to test the idea just the same. That’s why we’ve introduced the rotated and mirrored galaxy images. The mirror image of a clockwise spiral should appear anticlockwise, and vice versa. So, all the clockwise galaxies in our original data should now appear anticlockwise in the “bias study data,” and vice versa.
The specific type of bias we’re looking for is called sample bias. Scientists often take a sample of a thing by measuring properties of some number of that thing. We’ve asked you to classify many galaxies, and the sample consists of your classifications. If, as mentioned above, humans classify anticlockwise galaxies easier, then the classification sample will have more anticlockwise galaxies than the real universe. If our sample of galaxy classifications is not the same as the classifications of galaxies in the real universe, then any conclusions we draw about the universe from our sample will be wrong.
And we don’t want to be wrong. Scientists are, by nature, very careful. We want to think of every possible effect, and every possible interpretation of our data, before deciding on the right one. By being as careful as we can, we hope to increase our understanding of the real universe in which we live.
As always, we need your help to do this. See Kate’s status update on the forum, and keep classifying those galaxies!
Inside the first results
As Jordan’s already said, this blog is supposed to give you, our users and collaborators, a window into the research we’re doing. As I suspect most of you know, we’re working on a set of papers which will hopefully be submitted to a journal in the next month or so. The first set will probably contain four papers, and I thought I’d give you a run down of what each of these four is designed to do.
Although the whole team will be listed as authors (and we’ll include a link to the site which gives credit to those of you who have chosen to enter the names on the special page on the site), each is being led by a different team member. My paper is a general overview of the project, including a discussion of the process by which we’ve gone from clicks on the webpage to a catalogue of galaxies. The idea is to provide all the information that others working with our data might need in one place, and to avoid having to duplicate information in each of the individual papers.
Steven (in Portsmouth) is writing a paper that focusses on comparing the spirals and the ellipticals; he has to be more careful than most to account for the tendency of faint fuzzy things to be classified as elliptical galaxies, and has developed a whole set of tools to keep an eye on this. The results are excellent; we’ve always known that ellipticals tend to live in denser environment than their spiral counterparts, but with Galaxy Zoo we can really look at the details of this relation.
Kevin’s paper discards most of the galaxies to focus on some of the oddballs; the infamous blue ellipticals. Most elliptical galaxies are supposed to have finished star formation long ago, but these are still going strong. We’re planning to publish a list of these in the paper so hopefully other people will be able to follow them up alongside us.
Finally, Kate and Anze are leading the cosmology study, looking at the rotation direction of spirals. They’re desperate to get the bias study that’s now underway done so that their paper can be finished off – that’s the most critical thing at the moment so every classification you make gets us closer to being able to release the first science results.In the meantime you’ll hear more about each of these projects over the next week or two on this blog, but do comment in the meantime either here or on the forum.
I’ll finish with a couple of mea culpas – when I send out the email announcing our Christmas gift to you, I should have said that the link was on the left of the analysis page, and realised that for some of you it was the Summer Solstice. I won’t make either mistake again (just different ones). Chris
What this blog is all about…
Greetings, and happy holidays from Galaxy Zoo!We’ve really appreciated all the work you have done in classifying all the galaxies in the Zoo. If you haven’t been around for a while, we’d love it if you returned to the Galaxy Zoo site to classify a few more galaxies. If you haven’t already, please take a look at the Galaxy Zoo forum, where you can talk with fellow classifiers about the Zoo, astronomy, or anything else that strikes your fancy.
This blog is the latest project from the “Zookeepers”- the small but dedicated team that operates the site. Thanks to all of you, we now have a lovely sample of galaxies marked as “elliptical,” “clockwise spiral,” and so on. What we want to do now is to see what your classifications can tell us about the universe we live in. And oh my, are they telling us a lot about our universe. More than we ever imagined – and it seems like every week, we think of a new project we can do with your wonderful classifications.
Since you’re the ones who have done these classifications, it’s only fair that we keep you up to date on what we are doing.Here’s what happening now. We are busy analyzing the classifications in various ways; counting, sorting, measuring, and comparing our measurements to other scientists’. We are working on a number of projects right now. All of us are contributing to every project, but each project has one (sometimes two) people primarily responsible for it.
Soon, we will start communicating our results to other scientists. There are two main ways that scientists communicate with each other: meetings and papers. Meetings are the place to present work in progress and get feedback from other people, and papers are the written records of finished projects.* We will be giving two presentations at the American Astronomical Society (AAS) meeting in early January in Austin, Texas, USA. Chris will give a talk focusing on our research reuslts, and I will give a poster presentation on how the public has helped us create these projects. (More on this meeting as it gets closer.)
Along with preparing presentations for this meeting, we are also starting to write the scientific papers on our results.We created this blog to give you a window into the process by which we are conducting our research, and writing our papers. We’ll be doing a new post every Monday and Thursday, in the afternoon GMT (so, afternoons in the U.K. and mornings in the U.S.). We encourage you to leave comments here, and also to head over to the Forum to talk with other people.Coming up this Thursday – Chris will give an orientation of what we are working on, and who is doing what.
*No research project is really ever finished, because it always must be repeated and expanded upon, but papers are the place where results of a single project are recorded.
Welcome!
Welcome to the brand new Galaxy Zoo blog!
To start with, here’s a page with a bit of info about the project and what we hope to do with this blog.
Stay tuned for more!
Galaxy Zoo 