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Food deserts a mirage?
When a big public policy issue emerges, commentary tends toward solutions. Advocates for different solutions make all sorts of causal claims about why the problem has occurred and what could fix it. Often, though, it turns out there was never any problem to begin with.
Is “food deserts” one of these cases? A recent New York Times article suggests yes.
It has become an article of faith among some policy makers and advocates, including Michelle Obama, that poor urban neighborhoods are food deserts, bereft of fresh fruits and vegetables.
But two new studies have found something unexpected. Such neighborhoods not only have more fast food restaurants and convenience stores than more affluent ones, but more grocery stores, supermarkets and full-service restaurants, too. And there is no relationship between the type of food being sold in a neighborhood and obesity among its children and adolescents.
Within a couple of miles of almost any urban neighborhood, “you can get basically any type of food,” said Roland Sturm of the RAND Corporation, lead author of one of the studies. “Maybe we should call it a food swamp rather than a desert,” he said.
I have to admit I’m biased toward believing these studies, because the idea of contradicting an “article of faith” embraced by celebrities appeals to me. But was there ever any empirical evidence of food deserts to begin with?
It is unclear how the idea took hold that poor urban neighborhoods were food deserts but it had immediate appeal. There is even an Agriculture Department “food desert locator” and a “National Food Desert Awareness Month” supported by the National Center for Public Research, a charitable foundation.
But, Dr. Lee said, studies lending support to the idea tended to be limited by methodological difficulties.
For example, some researchers looked at neighborhood food outlets but did not have data on how fat residents were. Others examined small areas, like part of a single city and extrapolated to the entire nation. Others had a different problem. They looked at much bigger areas like ZIP codes, which include people of diverse incomes, making it hard to know what happened in pockets of poverty within those regions.
Some researchers counted only fast food restaurants and large supermarkets, missing small grocers who sold produce. Some tallied food outlets per 1,000 residents, which made densely populated urban areas appear to have fewer places per person to buy food. A more meaningful measure, Dr. Lee said, is the distance to the nearest stores.
“No Obesity Link to Junk Food in Schools”
NY Times reports:
Researchers at Pennsylvania State University tracked the body mass indexes of 19,450 students from fifth through eighth grade. In fifth grade, 59 percent of the children attended a school where candy, snacks or sugar-sweetened beverages were sold. By eighth grade, 86 percent did so.
The researchers compared children’s weight in schools where junk food was sold and in schools where it was banned. The scientists also evaluated eighth graders who moved into schools that sold junk food with those who did not, and children who never attended a school that sold snacks with those who did. And they compared children who always attended schools with snacks with those who moved out of such schools.
No matter how the researchers looked at the data, they could find no correlation at all between obesity and attending a school where sweets and salty snacks were available.
“Spacing Children Farther Apart Benefits Older Siblings”
Via the New York Times, this post at the Freakonomics blog caught my attention:
A new study (PDF here) by University of Notre Dame economist Kasey Buckles and graduate student Elizabeth Munnich finds that siblings spaced more than two years apart have higher reading and math scores than children born closer together. The positive effects were seen only in older siblings, not in younger ones.
The NYT post doesn’t address the selection issue–that those who choose to space their children apart may just be “better” parents than those who don’t. But the actual paper, and the Freakonomics post, does: the authors take advantage of the fact that some families wait between births due to factors beyond their control, i.e. miscarriages. This from the paper’s abstract:
However, because we are concerned that spacing may be correlated with unobservable characteristics, we also use an instrumental variables strategy that exploits variation in spacing driven by miscarriages that occur between two live births. The IV results indicate that a one-year increase in spacing increases test scores for older siblings by about 0.17 standard deviations—an effect comparable to estimates of the effect of birth order. Especially close spacing (less than two years) decreases scores by 0.65 SD. These results are larger than the OLS estimates, suggesting that estimates that fail to account for the endogeneity of spacing may understate its benefits.
Interesting stuff. So my question is whether the authors think they are going to convince policy makers that they should come up with incentives to influence birth spacing?
Boston Globe: “Who’s to blame for making parents paranoid?”
What parents really need is greater clarity about the safety margins. Otherwise, it’s only a matter of time before trust between parents and the parenting experts erodes, and parents simply reclaim reason and common sense as their guidepost for interpreting risk.
From here.
Seems, madam?
Weaving nutrition and exercise lessons into middle-school classrooms can reduce eating disorders among girls and ultimately save medical costs, a study by Boston researchers concludes.
The researchers analyzed data from an earlier study at 10 Massachusetts middle schools, including five that adopted an obesity prevention program called Planet Health, and five that did not.
…
Austin’s team estimated that if the obesity-prevention program they studied was expanded to 100 schools, there would be about $680,000 in health care savings.
From the article “Nutrition lessons for girls seem to pay off” in the August 2 Boston Globe. Commenters note small sample size and that this seems like an ad for “Planet Health” instead of an unbiased article.
Does TV affect kids’ sleep patterns?
Yes! screams this Boston Globe headline, “TV affects a child’s sleep patterns.”
Well, technically it’s probably true–I would wager there is at least one child in the world whose sleep patterns are affected by television, either negatively or positively. But for all kids? I’m not so sure.
Here’s the meat of the article:
Researchers from the Seattle Children’s Research Institute and the Department of Pediatrics at the University of Washington looked at sleep patterns and TV usage reported by parents for 612 children ages 3 to 5.
The 59 children who had a TV in their bedroom were more likely to report sleeping problems, including trouble falling asleep, nightmares, and trouble waking in the morning. Eight percent reportedly showed tiredness during the day compared with 1 percent of the rest of the group.
Putting aside the problems of selection bias (if your parent puts a TV in your room at age 3, maybe you had problems to begin with) and reverse causality (maybe kids with real trouble sleeping are given a TV so they will quiet down), I wonder what the purpose is of this study. Do we think that the types of parents who put a TV in their kids’ room will be swayed by these results?
Last, since this is the Globe’s “Be Well” column we get the following caveat:
CAUTIONS: The study relied on data reported by parents, so screen time may have been underreported.
That’s a problem, for sure; but the selection problem seems more problematic, as does the super-confident headline.
Causal effects of growing up with same-sex parents
The only way to measure the effects of a nontraditional upbringing is to wait until a large enough cohort gets old enough, so only in the past few years has there been data on whether children raised by same-sex parents were measurably different from those raised by heterosexual parents.
That’s an excerpt from an excerpt of a recent (June 16) blog post on the “Motherlode” blog on the New York Times web site. The post deals with whether kids raised by same-sex couples turn out any better or worse (as opponents of same-sex marriage apparently claim) than those raised by heterosexual couples.
It’s also wrong–that is, it’s not the case that the “only way” to tell this is from a longitudinal study. That type of study is neither necessary nor sufficient.
I’m not so interested in the substance of this question–in fact proponents may be doing themselves a disservice by focusing on this, because it’s such a silly question. But I found the summary of the data interesting. All of it suggests there are either no effects or positive ones, perhaps because same-sex couples are more likely to plan having children. Most of it’s correlational except for this, which I liked.
And, also for the first time, a control group of heterosexual families was used. The University of Virginia and George Washington University researchers studied preschoolers who were adopted at birth by 27 lesbian couples, 29 gay male couples and 50 heterosexual couples. (Yet another groundbreaking aspect to this study was the number of gay men who were included. To date, most of the research has been on lesbian mothers.)
What did they find? That it’s the quality of the parenting that creates a psychologically healthy child, not the sexual orientation of the parents.
Does facebook make kids depressed?
CHICAGO — Add “Facebook depression’’ to potential harms linked with social media, an influential doctors’ group warns, referring to a condition it says may affect troubled teens who obsess over the online site.
Researchers disagree on whether it is simply an extension of depression some teens feel in other circumstances or a distinct condition linked with using the online site.
But Facebook can be a particularly tough social landscape to navigate for young people already dealing with poor self-esteem, said Dr. Gwenn O’Keeffe, a Boston-area pediatrician and lead author of new American Academy of Pediatrics social media guidelines.
From an AP report via the Boston Globe. It’s harder to evaluate this information (aside from chortling) than some of the other posts I’ve been doing, since the details of it aren’t at all clear. We are told that “Researchers disagree on whether it is simply an extension of depression some teens feel in other circumstances or a distinct condition linked with using the online site,” which sounds like it can be translated as, “Researchers aren’t sure if it’s just a correlation or something more.”
That’s a nice caveat, but it’s poorly worded and I could see concerned parents reading over it and just concluding that Facebook = depressed kids.
Reports like these inevitably call to mind this cartoon.
Update: The Washington Post (actually, a blogger there) picked up the story, but without mentioning the caveat.