Tag Archives: methodology

Obesity as “social contagion”

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Findings in recent years that certain medical conditions, such as obesity, are strongly influenced by social networks have seemed to shake up thinking about how such conditions spread. A new model that explores obesity as a “social contagion” suggests obesity will eventually “spread” to at least 42% of the US population:

The social contagion hypothesis garnered widespread attention in 2007 when researchers from UC San Diego, documented that obesity can spread through a social network — just like viruses spread — because people “infect” each other with their perceptions of weight. That study was published in the New England Journal of Medicine, and subsequent research has confirmed the validity of the social contagion theory.

In a paper published Thursday in the journal PLoS Computational Biology, Harvard scientists applied a mathematical model of social contagion to 40 years of data from the Framingham Heart Study, a study that has followed more than 5,000 adult residents of Framingham, Mass., since 1948 to assess their heart health. Among the participants of that study, obesity increased from 14% in the 1970s to 30% in 2000 and continues to increase. Based on that data, the rapid upswing in obesity rates is due largely to social-network influence, said the authors of the new study. But, they noted, any subsequent rise in obesity rates will be slower than it has in the past. It may take another 40 years to reach that 42% obesity mark.

Interesting findings and I bet it is a complicated (but interesting) method by which such models are constructed.

If similar models were applied to other conditions or diseases, what are the results? In addition to obesity, what conditions are strongly influenced by social networks? Additionally, how can social networks be changed or altered so that an issue like obesity is combated?

Claim: “Facebook knows when you’ll break up”

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There is an interesting chart going around that is based on Facebook data and claims to show when people are more prone to break-up. Here is a quick description of the chart:

British journalist and graphic designer David McCandless, who specializes in showcasing data in visual ways, compiled the chart. He showed off the graphic at a TED conference last July in Oxford, England.

In the talk, McCandless said he and a colleague scraped 10,000 Facebook status updates for the phrases “breakup” and “broken up.”

They found two big spikes on the calendar for breakups. The first was after Valentine’s Day — that holiday has a way of defining relationships, for better or worse — and in the weeks leading up to spring break. Maybe spring fever makes people restless, or maybe college students just don’t want to be tied down when they’re partying in Cancun.

Potentially interesting findings and it is an interesting way to present this data. But when you consider how the data was collected, perhaps it isn’t so great. A few thoughts on the subject:

1. The best way to figure this out would be to convince Facebook to let you have the data for relationship status changes.

2. Searching for the word “breakup” and “broken up” might catch some, or perhaps even many ended relationships, but not all. Does everyone include these words when talking about ending a relationship?

3. Are 10,000 status updates a representative sample of all Facebook statuses?

4. Is there a lag time involved in reporting these changes? Monday, for example is the most popular day for announcing break-ups, not necessarily for break-ups occurring on that day. Do people immediately run to Facebook to tell the world that they have ended a relationship?

5. Does everyone initially “register” and then “unregister” a relationship on Facebook anyway?

The more I think about it, it is a big claim to make that “Facebook knows when you are going to break up” based on this data mining exercise.

Race as a lesser factor in forming friendships on Facebook

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A new study in the American Journal of Sociology finds that a shared racial identity was less important than several other factors when making friends on Facebook:

“Sociologists have long maintained that race is the strongest predictor of whether two Americans will socialize,” said Andreas Wimmer, the study’s lead author and a sociologist at UCLA…

In fact, the strongest attraction turned out to be plain, old-fashioned social pressure. For the average student, the tendency to reciprocate a friendly overture proved to be seven times stronger than the attraction of a shared racial background, the researchers found…

Other mechanisms that proved stronger than same-race preference included having attended an elite prep school (twice as strong), hailing from a state with a particularly distinctive identity such as Illinois or Hawaii (up to two-and-a-half times stronger) and sharing an ethnic background (up to three times stronger).

Even such routine facts of college life as sharing a major or a dorm often proved at least as strong, if not stronger, than race in drawing together potential friends, the researchers found.

Interesting findings – perhaps Facebook is a new world or younger generations don’t pay as much attention to race.

Additionally, it is interesting to read about the methodology of the study which took place at a school where 97% of students had Facebook profiles and the sociologists measured friendships in terms of photo tagging (and not who were actually listed as “friends”).

A couple of questions I have: is behavior on Facebook and choosing friends reflective of actual social patterns in the real world? Is there a selection issue going on here  – not all students or people of this age use Facebook so are college students who use Facebook already more likely to form cross-racial friendships?

Considering “polls gone wild”

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The Associated Press released a story yesterday with this headline: “Polls gone wild: Political gripes in Internet age.” It is an interesting read about the role polls have played in the 2010 election season and I have a few interpretations regarding the story.

1. The griping of politicians about polls does not often seem to be based on the methodology of the poll. Rather, I think the politicians are trying to curry favor with supporters and voters who are also suspicious of polls. I would guess many Americans are suspicious of polls because they think they can be manipulated (which is true) and then throw out all poll results (when there are methods that make the polls better or worse). Some of this could be dealt with by dealing with innumeracy and educating citizens about how good polls are done.

2. There is a claim that earlier polls affect later polls and elections and that overall, polls help determine election outcomes. Are there studies that prove this? Or is this just more smoke and mirrors from politicians?

3. If there are charges to be made about manipulation, it sounds like the political campaigns are manipulating the figures more than the reputable polling firms which are aiming to be statistically sound.

4. Stories like this remind me of the genius of RealClearPolitics.com where multiple polls about the same races are put side by side. If one doesn’t trust polls as much, just look at how polls compare over time. The more reputable companies show generally similar results over time. Basing news stories and campaign literature on just one poll may look silly in a few years with all of these companies producing numerous polls on almost a daily basis.

The presence of error in statistics as illustrated by basketball predictions

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TrueHoop has an interesting paragraph from this afternoon illustrating how there is always error in even complicated statistical models:

A Laker fan wrings his hands over the fact that advanced stats prefer the Heat and LeBron James to the Lakers and Kobe Bryant. It’s pitched as an intuition vs. machine debate, but I don’t see the stats movement that way at all. Instead, I think everyone agrees the only contest that matters takes place in June. In the meantime, the question is, in clumsily predicting what will happen then (and stats or no, all such predictions are clumsy) do you want to use all of the best available information, or not? That’s the debate about stats in the NBA, if there still is one.

By suggesting that predictions are clumsy, Abbott is highlighting an important fact about statistics and statistical analysis: there is always some room for error. Even with the best statistical models, there is always a chance that a different outcome could result. There are anomalies that pop up, such as a player who has an unexpected breakout year or a young star who suffers an unfortunate injury early in the season. Or perhaps an issue like “chemistry,” something that I imagine is difficult to model, plays a role. The better the model, meaning the better the input data and the better the statistical techniques, the more accurate the predictions.

But in the short term, there are plenty of analysts (and fans) who want some way to think about the outcome of the 2010-2011 NBA season. Some predictions are simply made on intuition and basketball knowledge. Other predictions are made based on some statistical model. But all of these predictions will serve as talking points during the NBA season to help provide some overarching framework to understand the game by game results. Ultimately, as Gregg Easterbrook has pointed out in his TMQ column during the NFL off-season, many of the predictions are wrong – though the makers of the predictions are not often punished for poor results.

New survey of Chicago Catholics

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On Wednesday, a new comprehensive report on Chicago Catholics will be released. The report is based on data from “524 Catholics in Cook and Lake counties” and the project was headed up by sociologist Andrew Greeley. Here are a few of the findings:

In addition, 78 percent of the respondents said Catholicism is either “extremely important” or “very important” in their lives.

Greeley wrote that the survey suggests “two separate Catholic identities — an imaginative, story-telling identity and a rules identity,” commonly referred to as “Cafeteria Catholics.” Those Catholics revere the sacraments and run in primarily Catholic circles, but they make their own choices on moral, religious and political issues.

“The only safe prediction seems to be that … there will be, whether the leadership likes it or not, varied forms of affiliation with a Church most of them still love,” Greeley wrote. “Not Cafeteria Catholics so much as Smorgasbord Catholics, a rich and diverse collection of ways to affirm one’s Catholicism.”

These findings about Catholics don’t seem too different than findings from other studies of American religion that show people of faith don’t follow all of the doctrines or practices of their faith traditions. Overall, people have some basic Christian beliefs or notions about spirituality but then a wide range of opinions on moral and practical issues.

A few questions about the methodology: 524 as a total N seems a little small plus I wonder why they went for Catholics in Cook and Lake Counties and not some of the other collar counties. This reminds me that on maps that show the religious plurality in each American county, DuPage County is coded Catholic. I’d also be curious to know whether Latino Catholics, of which there are a large number in the Chicago region, have different views than other Catholics.

Predicting the fastest growing American cities for the next 40 years

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Forbes has a new list of what they think will be the fastest growing cities in the United States in the next 40 years. Not surprisingly, the top 5 are all in the South and West. Perhaps surprisingly, these cities are “little big cities,” places that grown in the last few decades and are poised for new growth. Here are the top cities for growth: Raleigh-Durham, North Carolina; Austin, Texas; Salt Lake City, Utah; San Antonio, Texas; Oklahoma City, Oklahoma.

Forbes says they are using a different methodology to select these cities:

In developing this list we have focused on many criteria–affordability, ease of transport and doing business–that are often ignored on present and future “best places” lists. Yet ultimately it is these often mundane things, not grandiose projects or hyped revivals of small downtown districts, that drive talented people and companies to emerging places.

This methodology seems to emphasize “softer factors” like affordability and quality of life. I almost wish we could just fast forward forty years to see how accurate this is. What would others predict and what factors would they use?

But I can see some of the logic. These places offer some of the amenities of the big city and are vibrant places where things are happening. Couple this with affordable homes, some jobs, and less congestion and I could see how it is appealing. Additionally, 8 out of the top 10 are in the South and West – only Columbus, Ohio and Indianapolis, Indiana are outside these regions. It would make sense that the growing areas of the country are the places where these mid-sized cities are growing.

The ever-expanding trolley problem

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For those who study moral dilemmas, the trolley problem is a common hypothetical situation. But the trolley problem keeps expanding to gather more information on how we make choices in such situations: the trolley problem can now include a spur track or a Lazy Susan.

Additionally, there is an interesting discussion about the value of “trolleyology.”

A word cloud as an accurate information graphic

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There are many ways to visually present data or statistics. One issue can arise when parts of graphs or images are not displayed in the correct proportions. Does using a word cloud fall into these difficulties?

Gallup has put together a word cloud of American’s perceptions about the federal government. Some phrases, such as “too big” and “corrupt” are much bigger. Some words are on their sides such as “good” and “terrible.”

Overall, I would say the word cloud is probably not the best choice in this situation. It is hard to judge the most popular responses and the relative proportions of each response. While one can quickly pick up that the majority of responses were negative, it is not a very precise graphic.

How to keep the seat next to you on the train empty

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Chris Wilson examines an argument recently made by a writer about how he is able to keep the seat next to him on the train empty:

In an op-ed in today’s New York Times, Wideman describes how, during his regular commute between New York City and Providence on the Acela, he almost always enjoys a double seat to himself. I call that divine intervention. He chalks it up, after considering and rejecting the alternatives, to being black…

Wideman, a successful writer, describes his observations as a “casual sociological experiment.” But he lacks any controlled variables. Granted, the only direct way I can think of to test his hypothesis would be to adjust his complexion while holding everything else—dress, demeanor, reading material—as constant as possible. The ethics of doing this notwithstanding, the makeup is murderous to your pores.

A couple of thoughts:

1. It would not surprise me at all if race was the important factor in this situation.

2. But this is a nice illustration of how one could go about testing this hypothesis: devise an experiment where the person next to the empty seat alters their appearance/features and then sees how people respond.