Social Science Statistics Blog

5 August 2008

Gans and Leigh on the "Baby Bump"

In a Born on the First of July: An (Un)natural Experiment in Birth Timing, forthcoming at the Journal of Public Economics, Joshua Gans and Andrew Leigh examine "introduction effects" (the extent to which people change their behavior to respond to new policies) in the context of a baby bonus that was initiated in Australia in 2004. In May of that year, the government announced that families of babies born on or after July 1 would receive a $3000 cash bonus. Mothers with due dates around that time made special arrangements (mostly delaying Caesarean and other planned deliveries) to get the prize. The authors estimate that over 1000 births were moved; July 1, 2004, witnessed more births than any other day in the period since 1975 for which the authors have data.

Continue reading "Gans and Leigh on the "Baby Bump""

Posted by Andy Eggers at 8:02 AM | Comments (1)

26 June 2008

Exxon-tainted research?

A few bloggers at other sites (Concurring Opinions and Election Law Blog) have pointed out an interesting footnote in the Supreme Court's recent decision on punitive damages in the Exxon Valdez case. Justice Souter took note of experimental research on jury decisionmaking done by Cass Sunstein, Daniel Kahneman, and others, but then dismissed it for the purposes of the decision because Exxon had contributed funding for the research:

The Court is aware of a body of literature running parallel to anecdotal reports, examining the predictability of punitive awards by conducting numerous “mock juries,” where different “jurors” are confronted with the same hypothetical case. See, e.g., C. Sunstein, R. Hastie, J. Payne, D. Schkade, W. Viscusi, Punitive Damages: How Juries Decide (2002); Schkade, Sunstein, & Kahneman, Deliberating About Dollars: The Severity Shift, 100 Colum. L. Rev. 1139 (2000); Hastie, Schkade, & Payne, Juror Judgments in Civil Cases: Effects of Plaintiff’s Requests and Plaintiff’s Identity on Punitive Damage Awards, 23 Law & Hum. Behav. 445 (1999); Sunstein, Kahneman, & Schkade, Assessing Punitive Damages (with Notes on Cognition and Valuation in Law), 107 Yale L. J. 2071 (1998). Because this research was funded in part by Exxon, we decline to rely on it.

It will be interesting to see whether this position is taken up by the lower courts; if so, we might see less incentive for private actors to fund social science research. That could be good or bad, I suppose, depending on one's views of likelihood that researchers will be unduly influenced by their funding sources.

Posted by Mike Kellermann at 1:13 PM | Comments (8)

13 June 2008

Awards for IQSS faculty

Two awards given by the Society for Political Methodology were announced today, and both of them went to IQSS faculty members (and co-authors).

The Gosnell Prize is given to the "best paper on political methodology given at a conference", and this year's prize was awarded to Kevin Quinn for his paper "What Can be Learned from a Simple Table? Bayesian Inference and Sensitivity Analysis for Causal Effects from 2x2 and 2x2xK Tables in the Presence of Unmeasured Confounding." From the announcement:

Quinn's paper offers a set of steps to improve inference with binary independent and dependent variables and unmeasured confounds. He derives large sample, non-parametric bounds on the average treatment effect and shows how these bounds do not rely on auxiliary assumptions. He then provides a graphical way to depict the robustness of inferences as one changes assumptions about the confounds. Finally, he shows how one can use a Bayesian framework relying on substantive knowledge to restrict the set of assumptions on the confounds to improve inference.

The Warren Miller prize is given annually to the best paper appearing in Political Analysis. This year's prize has been awarded to Daniel E. Ho, Kosuke Imai, Gary King, and Elizabeth A. Stuart for their article, "Matching as Nonparametric Preprocessing for Reducing Model Dependence in Parametric Causal Inference." The abstract of their paper follows:

Although published works rarely include causal estimates from more than a few model specifications, authors usually choose the presented estimates from numerous trial runs readers never see. Given the often large variation in estimates across choices of control variables, functional forms, and other modeling assumptions, how can researchers ensure that the few estimates presented are accurate or representative? How do readers know that publications are not merely demonstrations that it is possible to find a specification that fits the author's favorite hypothesis? And how do we evaluate or even define statistical properties like unbiasedness or mean squared error when no unique model or estimator even exists? Matching methods, which offer the promise of causal inference with fewer assumptions, constitute one possible way forward, but crucial results in this fast-growing methodological literature are often grossly misinterpreted. We explain how to avoid these misinterpretations and propose a unified approach that makes it possible for researchers to preprocess data with matching (such as with the easy-to-use software we offer) and then to apply the best parametric techniques they would have used anyway. This procedure makes parametric models produce more accurate and considerably less model-dependent causal inferences.

Posted by Mike Kellermann at 2:22 PM | Comments (0)

31 May 2008

The Tree-Friendly Academic, Part II: The Editing Process, and Getting Off the Monitor

I'm grateful for the strong response to my original query for quality, free PDF annotation for Linux. In general, there seem to be a few categories.

-Windows-based editors, adaptable through emulators: PDF X-change, Foxit (free version), primopdf
-Linux editors with non-portable annotations: Okular, which has hidden XML files for its annotations (skim, for OS X, has the same scheme)
-early, incomplete solutions that will eventually be good: GNU's PDF project, Xournal
-early, incomplete solutions that aren't user-friendly: pdfedit, Cabaret Stage
-early solutions that are still in progress: evince

Of all of these options, I like Okular the best, mainly because integrating its XML-saved annotations into the PDF is but one plugin away (which might already exist, for all I know), and it's theoretically portable to Windows by installing qt4 binaries. Using an emulator like wine is a hassle big enough that I've avoided it, for the same reason I don't use cygwin on Windows systems.

So we're close to a (more) universal free editing environment. But I'm still not a fan of doing all my work on a screen, and also not willing to print. So I'm trying a middle road.

Continue reading "The Tree-Friendly Academic, Part II: The Editing Process, and Getting Off the Monitor"

Posted by Andrew C. Thomas at 11:05 PM | Comments (5)

26 May 2008

The Tree-Friendly Academic: Whither A Useful Free PDF Editor?

I'm a Linux user in need of a quality PDF reader with basic annotation tools, and I need it to be available for free. Think I'm asking for too much?

We're at a point where the level of content available online dwarfs our ability to print it all onto paper for examination and notation. As academics, we're expected to sort through volumes of other people's work in order to verify that our own is original, as well as comment, annotate, and on occasion make corrections or forward-references to later works.

But despite a boom in computational power and information bandwidth, the software to do this without resorting to printed or copied matter isn't accessible to most students without paying through the nose. Full software suites like Adobe Acrobat aren't necessary for the kind of work academics need to do. There are a few functions that are essential to the task, currently available in commercial software:

-Adding and reading notes, whether free-floating or attached to highlighted text
-The ability to select and copy multi-column text (none of the free ones seem to be able to get this one right)
-I'd like that when LaTeX creates a link to a footnote or citation, hovering over the displayed link should cause a pop-up box to display the information.

I'm a man with big ideas but no time, and more importantly, no budget, to motivate and drive the development and use of a free PDF reader with mild annotation capabilities. I can't resort to the for-pay software available from the school website because I'm running Linux, and I shouldn't have to go to a virtual machine or another computer to do this kind of annotation. Likewise, others shouldn't have to spend hundreds for software where they only need a few simple functions.

I suppose the issue is that everyone has their own toys they want included in a PDF editor, which is why the commercial package makes sense. But as academics, wouldn't we be happy with "the basics plus"?

Posted by Andrew C. Thomas at 6:34 PM | Comments (21)

22 May 2008

Nicholas and James are Featured in the NYT again

Professor Nicholas Christakis and Professor James Fowler’s study on social network and smoking cessation is featured in the New York Times, which is also going to appear in the New England Journal of Medicine this Thursday. Congratulations to them!

Their basic findings are that smokers are likely to quit in groups (As Nicholas said, “Whole constellations are blinking off at once.”) and that the remaining smokers tend to be socially marginalized.

One interesting question I have for their study is that, if friends tend to quit smoking together, will this partly contribute to the simultaneous weight gains among friends, a result Nicholas and James have found last year using the same dataset? In other words, I totally accept that social ties have important impacts on individuals' wellbeing, but if you try to research a certain outcome of wellbeing and do not control for the “contaminating” effects from other outcomes, the estimation of the social network effects on the former outcome could be biased. For example, the weight gains among friends, from this point of view, could be partially resulted from their simultaneous quitting from smoking. Of course, if smokers only consist of a very small fraction of the participants in the studied sample and their weight changes are not too extreme, the bias of the estimation should not invoke a serious problem.

See the following link for a glimpse of their study.

Study Finds Big Social Factor in Quitting Smoking
http://www.nytimes.com/2008/05/22/science/22smoke.html?partner=rssnyt&emc=rss

Sorry for the duplicate if you have noticed this news.

Posted by Weihua An at 12:01 PM | Comments (2)

20 May 2008

Matching Portfolios

Jointly with Dave Kane, an IQSS fellow and head of Kane Capital, I've been working on applying causal inference techniques to the financial problem of performance evaluation. We have a draft on SSRN up here.

Continue reading "Matching Portfolios"

Posted by Kevin Bartz at 11:10 PM | Comments (3)

19 May 2008

Harvard Program on Survey Research (on Youtube)

Mark Blumenthal from pollster.com has been posting interviews with scholars at the 2008 AAPOR conference, including two with our very own Sunshine Hillygus and Chase Harrison from the Program on Survey Research:

Posted by Mike Kellermann at 10:50 AM | Comments (0)

15 May 2008

Placebo effects and the probability of assignment to active treatment

I just finished reading an interesting paper on placebo effects in drug trials by Anup Malani. Malani noticed that participants in high probability trials know that they more likely to get active treatment (because of informed consent prior to the trial). They have higher expectations and hence should have higher placebo effects than patients in low probability trials. Malani compares outcomes across trials with different assignment probabilities and finds evidence for placebo effects. A related finding is that the control group in high probability trials reports more side effects.

The paper discusses some potential implications of placebo effects, e.g. that patients who are optimistic about the outcome might change their behavior and hence get better even without the active drug. It makes me wonder how this might translate into non-medical settings and whether there are studies of placebo effects in the social sciences. Also, if placebo drugs can improve health outcomes, maybe ineffective social programs would still work as long as participants don’t know whether the program works or doesn’t? Maybe this is the role of politics. But what about the side-effects?

Malani, A (2006) “Identifying Placebo Effects with Data from Clinical Trials” Journal of Political Economy, Vol. 114, pp. 236-256. http://papers.ssrn.com/sol3/papers.cfm?abstract_id=901838

Abstract:
A medical treatment is said to have placebo effects if patients who are optimistic about the treatment respond better to the treatment. This paper proposes a simple test for placebo effects. Instead of comparing the treatment and control arms of a single trial, one should compare the treatment arms of two trials with different probabilities of assignment to treatment. If there are placebo effects, patients in the higher-probability trial will experience better outcomes simply because they believe that there is a greater chance of receiving treatment. This paper finds evidence of placebo effects in trials of antiulcer and cholesterol-lowering drugs.

Posted by Sebastian Bauhoff at 12:00 PM | Comments (7)

13 May 2008

IN, NC Rehash; WV Prediction

I know this isn't my normal day, but three points today:

• How I did in IN and NC


• My prediction for WV

Error	Actual	Predicted

Continue reading "IN, NC Rehash; WV Prediction"

Posted by Kevin Bartz at 5:48 PM | Comments (4)