What can your dentist tell you about your risk for ovarian cancer?

/ bs king / 27 Comments

Answer: more than I thought.

The absolute rates aren’t small either…20% of women with epithelial ovarian cancer have hypodontia, as opposed to 3% of women overall.  Women are 4 times as likely to have hypodontia as men.
I bring this up because I think it’s an interesting clear case of correlation without causation.  Missing teeth don’t cause ovarian cancer, and ovarian cancer doesn’t cause missing teeth.  It’s also an interesting case of how research has to move in two directions.  Now that there’s proof that ovarian cancer patients tend to have hypodontia, there are trials underway to see if women with hypodontia get ovarian cancer, and if so how high the rate is.  A correlation also does not mean prediction.  Prediction means prediction.
If you’re wondering why this came up, it’s because I have hypodontia, and I’d never really thought to look it up until now*.  Apparently it’s a half decent idea for me to let my primary care doctor know about this, as there are very few early signs of ovarian cancer.  Science….it never fails to surprise me.**
*Sometimes I forget we have the internet.  Not really, but sometimes there are questions I had pre-internet that it never occurs to me I can get answers to now.  I found out about the teeth thing when my teeth failed to develop, back in around 1993 or so.

**In case you’re really curious about my dentistry: I’m congenitally missing 8 teeth total, but 4 of them are my wisdom teeth. To be clear, these were not pulled, they never existed.  Wisdom teeth (third molars) don’t count in the diagnosing of hypodontia.  I’m completely missing my mandibular second molars, and I only have baby teeth for my mandibular second bicuspid (second premolar).  None of this is visible unless you’re seriously looking in my mouth, but dentists do generally go “oh cool!” when they see my mouth for the first time.  The teeth I’m missing are all the most common ones, though 4 is on the high side to be missing (all the people in the study were only missing one or two).  I also had a tooth try to grow in on the roof of my mouth, but that’s a whole different story.

P(x|y) = eww, gross

/ bs king / 4 Comments

I finished my first midterm of the semester this week.  There was a decent section that revolved around calculating P(x|y)….in other words the probability of x if we know that y has already happened.  In simple terms, if you have a probability of something happening (x), and something else that’s related to x happens (y), the probability of x happening changes.

This is not an overly complex concept when it’s spelled out mathematically, but in real life it can be hard for people to remember that improbable events are often far more probable if you consider what’s already happened.

I was reminded of this when I was reading Dear Prudence (Slate.com’s advice column) last week and came across this letter from a man (born by artificial insemination from an unknown sperm donor) who decided to seek out his father, only to discover that it was the same man who had donated to his wife’s mother.  Oops.  And gross.  Seriously, gross.

What struck me as more though, was a response that was printed from another reader:

I know you/we cannot know, but color me skeptical that this letter is legit. The odds of such a “match” have to be very small. I can’t help but wonder if this letter is a fiction pushing a political agenda.

This seems true of course…I mean, it’s a sort of Casablanca moment right?  Of all the gin joints in all the towns in all the world….

But let’s think about this couple for a second:

  1. They’d be the same age.  I don’t know about sperm banks in particular, but I do know that most stored bodily fluids are only considered “good” for a few years…so if two people were to result from one donor, they would likely be around the same age.  Most people tend to marry someone within a few years plus or minus their own age.
  2. They’d be from the same place. Sperm donors are unlikely to trit trot around the country donating to various centers….they’re more likely to stay in the city they actually live in.  I have no particular experience with this, but I’d imagine that people looking for a sperm bank stick to their same town as well….which means these two children would like be raised in the same city, making their chances of meeting go up and the culture they were raised in more similar.
  3. Their mothers had a lot in common.  From the letter, the couple is at least over the age of 30.  From what I gather, it was less common for people to use sperm banks prior to 1980.  According to this article, in 1987, only 5000 single women asked for donor sperm.  At the time the letter writers mother and mother-in-law were looking, it was likely even fewer.  This means the two shared a very unique background, and had mothers who were both counter-cultural enough to go forward with this.  This would give them quite a bit in common.
  4. They’d likely have at least some similar hobbies, interests, and personality traits. I think most people would agree that at least some of our hobbies/interests/personality traits/taste in friends/what have you are more nature than nurture.  I would thus think it extremely likely that two people sharing the same father would have at least one major hobby or interest in common, making it much more likely that their social circles would cross and that they’d have something to talk about when it did.  The more you believe genetics influence who you eventually are, the better the chances they’d meet.
  5. People (might) like people who look like them.  I actually had some trouble finding a good paper that proves this, but it’s a theory.  Interestingly, the only scholarly article cited in support of this on the Wikipedia page actually turned out to say they found no evidence of this.  This is why Wikipedia =/= research.
  6. Their parents would likely have supported the union.  In-law issues are tough, but I’d imagine if you were a lesbian mother in the 80s and found out your adult son was going to marry the daughter of another lesbian mother from the 80s, you’d be pretty psyched.  Also, they’d very likely have been in a similar socio-economic class, as both their moms were well off enough to pursue this avenue.
So we’re not calculating the probability of two random people finding each other.  We’re calculating the probability that two people in the same age group, from the same city, with the same unique background and similar interests, from similar cultures, with some similar personality traits, who looked similar, would meet, start dating and with (likely) large amounts of family support get married.  The chances would still likely be small, but not nearly as small.  When you throw in that they ended up at the same college, the chances actually get pretty high.
Many people seems to think that we have some sort of “incest flag” that would make us not attracted to relatives, but it actually is more likely related to the Westermark effect…or being in close proximity during childhood.  While it appears sperm banks are now actually trying to account for this, there could be some scary ramifications for some people.  Kinda brings new meaning to the phrase “what’s your name, who’s your daddy?” eh?

Who talks more…men or women?

/ bs king / 3 Comments

There is nothing I love more than a clever phrase to describe a phenomena that bothers me.  Last night I found such a phrase in a Jezebel article about gender differences in number of words spoken per day.

The phrase: public domain data.
This describes the phenomena of data that’s been so often cited that no one seems to think you need a reference for it anymore (think “you need 8 glasses of water per day”).  
In this particular article, she brings it up in the context of the assertion that women say more words per day than men do.  The most commonly cited data puts it at anywhere from double to quadruple the number…quite a difference by any stretch of the imagination.  The problem is the numbers are apparently quite fictional.
The Jezebel piece links to this piece on a blog from UPENN where someone actually tried to track down a study that ever established the numbers quoted.  They found that it apparently originated with James Dobson sometime in the late 80’s or early 90’s, and that he did not seem to have a study to back him up (his actual quote was that “God gave women 50,000 words for the day, and men 25,000”).
From there it seems to have changed and distorted, but it does not seem anyone has actually sat down and counted the number of words men and women said.
If you think about it, this would be a really hard study to do.  I mean, I think most people would knee-jerk agree that women talk more than men, but we have to remember that we’re only thinking of social situations. Your choice of profession would HEAVILY skew how many words you were saying per day.  I mean, my brother the biology teacher is by far the quietest member of my immediate family when we get together.  However, I would hazard a guess that 5 days out of the week he likely says more words than I do.  I mean, he teaches.  He has to say words.  I spend at least half my day analyzing data.  No words needed.  I also have a longer commute (no talking needed) and unless I’m giving a presentation all of my meetings involve giving people equal time to talk.  But of course people who met us wouldn’t count his professional speaking. It would be clear to everyone that I talk more…unless you had a researcher study us on an average day.
Additionally, even if this stat had been true in 1993, how would we count it today?  In 1993, most social communication was verbal.  How would we count blogging, Twitter, Reddit or texting? It feels strange to count those as words, but also strange to not include them.  
I mean, the little lord’s been taking his morning nap for the past hour or so.  In that time I have commented on 4 blogs, written two emails, one Facebook message, and written this post.  For research purposes though, I haven’t said a word.  Interesting, isn’t it?

Friday Fun Links 2-22-13

/ bs king

Now that Valentine’s Day is over, I thought you might want to know how to break up with someone, data style.

An American accent quiz.  I just spent some time out west, is this why I apparently sound like I’m from there?
Fun fact: Britain has only failed to invade 22 in the world.  What did Guatemala do wrong?

Remember the Sims?  Here’s what happens when they go wrong.

This is a little surreal looking, but these fMRIs of fetal brains are really interesting.

Going out to Utah reminded me that my first science crush was paleontology.  Here’s a size comparison chart of people and dinosaurs.  Expect more dinosaur mentions in the weeks to come.

Who do you believe, me or your brain?

/ bs king / 3 Comments

A few years ago, right before the 2008 election, a friend of mine put the following up on Facebook:

This was accompanied by a blurb that we should all think about these wise words from a great man.  
Now I haven’t taken a history class since 1999, but something about the language struck me as funny.  I wasn’t sure, but it didn’t sound like Lincoln to me.  Thusly, I ran to the Google and took a look around.  I found the Snopes page and the Illinois Historical Society site…both confirmed my suspicions.  Lincoln never said that.  
Back then I was young and naive, so I blithely left a link for my friend letting him know the author was wrong, and that it was actually William Boetker who said it.  A few days later, I decided to check if anything else had happened with the post….and found that he had deleted me as a friend, deleted my comment, but left the post up.
It was baffling to me that someone could take that much offense not because I had disagreed with the content, but because I had pointed out a legitimate factual error in something he was citing.  It was my introduction to this sort of thing (which I think has become more common as the internet has grown) but it gets me every time.  Obviously I understand why people want their opinions to be right, but must everything that defends ones point be true?
I’ve had a few other incidents like this recently, and so I was really interested to hear about this  study done in partnership with Slate.com, where they presented people with photos of political events since 1999. The twist was the 5 of the possibilities (participants were given a random sampling of 4)  were doctored photos depicting events that never happened.  They were then asked if they either saw it or remembered it happening.  
I’m sure you can see where this is going.
Quite a few people “remembered” the false events (all of which could be viewed as negative against a particular politician).  While some merely checked the box, others had detailed memories they wrote down (ie “that was the day I lost all respect for Hilary Clinton”).  What really got me interested were two things:
First, Democrats were more likely to “remember” the false events that made Republicans look bad, and Republicans were more likely to “remember” moments that made Democrats look bad.  Additionally, regardless of party, the more strongly you said you remembered it, the more people couldn’t recognize events as false even when they were told there was a false one out of the ones they’d remembered.
Now there are some limitations to this study*, but I wonder if it’s not starting to touch on the same phenomena.  Once we start to believe a piece of information is true, are we more likely to keep believing it or to consider certain points of falseness less relevant?  If it aligns with our previously held beliefs, are we even more likely to do this?  
Why else would you hold on to a quote/fact/etc that had a demonstrably false portion?
*Only 5% of those survey were conservative, it was Slate readers polled, nothing stopped them from looking things up during the survey

Wednesday Brain Teaser 2-20-13

/ bs king / 5 Comments

I am thinking of a number between 1 and 1300.  It meets 3 criteria:

  1. It is a perfect cube.
  2. It is less than 500.
  3. It is a perfect square.
Just kidding, it only meets two of those.  To make up for lying though, I’ll tell you that it starts with 5, 7, or 9.

Include in your answer how much googling it took you.

Fox news: the channel you love to hate

/ bs king / 3 Comments

At least according to this chart of people’s most and least trusted TV news sources:

I’m deeply curious how many of the people who ranked anything as their “least trusted” actually arrived at that assessment after watching that particular channel.  This feels like a poll that’s a lot more about social signaling than about actual assessment of new sources.
Here’s the original poll.  

Data, elections, and how to check your facts

/ bs king / 2 Comments

I’ve been meaning to post something on David Brooks (Brooks’s? Brooks’?) column from a few weeks ago on the “Philosophy of Data”.  A couple readers sent this to me (thanks all!) and I thought it was pretty interesting.  He questions how the rise of big data is going to change things, and raises a few pertinent questions:

Over the next year, I’m hoping to get a better grip on some of the questions raised by the data revolution: In what situations should we rely on intuitive pattern recognition and in which situations should we ignore intuition and follow the data? What kinds of events are predictable using statistical analysis and what sorts of events are not?

I think those questions are relevant, and I was thinking about them when this cartoon popped up in my newsfeed on Facebook a few days ago:

In the post election fallout, a lot of the geek blogs I read questioned deeply Romney’s data collection.  Several supposed insiders claimed that while there were many in his campaign charged with data collection, he lacked people who were performing what is scientifically known as “the sniff test”.
Now I have no idea if the stuff about the Romney campaign is true (though I did know some folks on the Obama team and their data gathering was quite stunning to the point of mildly creepy), but I think that raising questions about data vs gut reactions are going to be big battles in areas like politics.  I mean, anyone who’s seen or read Moneyball knows that it took a while to get this in to baseball, and baseball’s got far fewer moving targets than politics.
What I think is interesting though is that integrating large data sets in to a highly charged and changing environment actually isn’t that hard, and I’m not sure why intuition and data get set up as opposing forces.  They actually work quite well together if you let them.  Here’s the basic steps:
  1. Figure out what problem you’re trying to solve
  2. Get a large relevant data set
  3. Analyze it until you get any numbers you can think of that might be helpful
  4. Find several rational people who are deeply embedded in the problem area
  5. Ask them what they think of the data, get the gut reaction
  6. Explain to them where you got the data, see if their reaction is the same
  7. Ask them if anyone they know would disagree with this data, and if so why
  8. Ask them if this helps them know how to proceed
  9. Ask them if there’s any other data that might be useful for this problem
  10. Go find that, repeat 5-9.
Data is helpful, but easily manipulated.  We need a combination of data and good gut reactions to figure out where to go in high stakes environments.  People directly involved in a situation are always going to be both the best and worst judge of the situation….and that’s okay.  Data geeks should set themselves somewhere in the middle, and always be questioning.  Data doesn’t make you an expert, but it can give you standing to challenge the experts. 
There’s no magic bullet here.  There’s only another very useful tool in (what should already be) a well stocked tool box.  

Interesting conference data of the week

/ bs king / 3 Comments

So tonight’s the last night I’m at this conference (American Society for Bone Marrow Transplant if you’re curious), so I figured it would be an appropriate moment to share some interesting data issues that came up in the sessions I went to.

The most interesting one came from a group out of Johns Hopkins, in their talk about their combined inpatient/outpatient program.  About 20 years ago now, they started to transition their transplant patients from one long inpatient stay to a shorter stay with a sort of intensive outpatient clinic follow up.  This worked really well, cut costs, helped patients feel more autonomous, etc.  What was interesting is that as they followed up on patients and how they did, they found that patients treated under this model did better on every single quality of life metric* except one: feelings about appearance.

Since there is no reason to believe they actually looked any different, the only conclusion they could reach is that the more “normal” people the cancer patients saw, the more acutely aware they were of how they looked.  When they were in the hospital, they were surrounded by other patients, but on the outside they were exposed to more healthy people.

I thought that was an interesting example of how much quality of life measures can depend on what your environment is and who you’re being exposed to.  We like to act like hapiness or contentment were definitive values that are totally internally generated, but they’re not.  People compare themselves to others.  We just can’t help it.

*The hard health measures (recovery, blood counts, etc) were the same with either method.