andrew_gelman_stats andrew_gelman_stats-2010 andrew_gelman_stats-2010-257 knowledge-graph by maker-knowledge-mining
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Introduction: Andrew Eppig writes: I’m a physicist by training who is transitioning to the social sciences. I recently came across a reference in the Economist to a paper on IQ and parasites which I read as I have more than a passing interest in IQ research (having read much that you and others (e.g., Shalizi, Wicherts) have written). In this paper I note that the authors find a very high correlation between national IQ and parasite prevalence. The strength of the correlation (-0.76 to -0.82) surprised me, as I’m used to much weaker correlations in the social sciences. To me, it’s a bit too high, suggesting that there are other factors at play or that one of the variables is merely a proxy for a large number of other variables. But I have no basis for this other than a gut feeling and a memory of a plot on Language Log about the distribution of correlation coefficients in social psychology. So my question is this: Is a correlation in the range of (-0.82,-0.76) more likely to be a correlatio
sentIndex sentText sentNum sentScore
1 Andrew Eppig writes: I’m a physicist by training who is transitioning to the social sciences. [sent-1, score-0.251]
2 I recently came across a reference in the Economist to a paper on IQ and parasites which I read as I have more than a passing interest in IQ research (having read much that you and others (e. [sent-2, score-0.23]
3 In this paper I note that the authors find a very high correlation between national IQ and parasite prevalence. [sent-5, score-0.334]
4 82) surprised me, as I’m used to much weaker correlations in the social sciences. [sent-8, score-0.328]
5 To me, it’s a bit too high, suggesting that there are other factors at play or that one of the variables is merely a proxy for a large number of other variables. [sent-9, score-0.397]
6 But I have no basis for this other than a gut feeling and a memory of a plot on Language Log about the distribution of correlation coefficients in social psychology. [sent-10, score-0.605]
7 So my question is this: Is a correlation in the range of (-0. [sent-11, score-0.316]
8 76) more likely to be a correlation between two variables with no deeper relationship or indicative of a missing set of underlying variables? [sent-13, score-0.714]
9 My reply: First off, I don’t think you can ever distinguish between correlations of . [sent-14, score-0.226]
10 I don’t think you can treat the high correlations as evidence against their argument. [sent-19, score-0.256]
11 Finally, are you related to the first author of the linked article, or is it just that you did a search on Eppig and encountered this stuff? [sent-21, score-0.305]
12 Eppig responds: I am in fact related to the first author of the study — he’s my brother. [sent-24, score-0.245]
13 Since my first question, I’ve been wondering about how to interpret the results of a regression when some of the dependent variables have been imputed via regression. [sent-25, score-0.666]
14 + xn) where x1 has had its missing values imputed using: fit. [sent-30, score-0.402]
15 + xn) Are there extra considerations required in interpreting the model fit. [sent-34, score-0.226]
16 Can one read off the coefficient values and errors from fit. [sent-36, score-0.289]
17 Naively, I feel that the errors in xn are now correlated with the other independent variables and a simple linear regression is no longer appropriate/valid. [sent-40, score-0.826]
18 Are the coefficients of x1, x2,…, xn valid but the errors invalid? [sent-41, score-0.639]
19 In general you want to fit both models together, or, in general, to model all the variables jointly. [sent-43, score-0.306]
20 That said, in practice I’ll typically just take the imputed x-values as exact and not think too hard about it. [sent-44, score-0.23]
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Introduction: Andrew Eppig writes: I’m a physicist by training who is transitioning to the social sciences. I recently came across a reference in the Economist to a paper on IQ and parasites which I read as I have more than a passing interest in IQ research (having read much that you and others (e.g., Shalizi, Wicherts) have written). In this paper I note that the authors find a very high correlation between national IQ and parasite prevalence. The strength of the correlation (-0.76 to -0.82) surprised me, as I’m used to much weaker correlations in the social sciences. To me, it’s a bit too high, suggesting that there are other factors at play or that one of the variables is merely a proxy for a large number of other variables. But I have no basis for this other than a gut feeling and a memory of a plot on Language Log about the distribution of correlation coefficients in social psychology. So my question is this: Is a correlation in the range of (-0.82,-0.76) more likely to be a correlatio
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Introduction: Sandeep Baliga writes : [In a recent study , Gilles Duranton and Matthew Turner write:] For interstate highways in metropolitan areas we [Duranton and Turner] find that VKT (vehicle kilometers traveled) increases one for one with interstate highways, confirming the fundamental law of highway congestion.’ Provision of public transit also simply leads to the people taking public transport being replaced by drivers on the road. Therefore: These findings suggest that both road capacity expansions and extensions to public transit are not appropriate policies with which to combat traffic congestion. This leaves congestion pricing as the main candidate tool to curb traffic congestion. To which I reply: Sure, if your goal is to curb traffic congestion . But what sort of goal is that? Thinking like a microeconomist, my policy goal is to increase people’s utility. Sure, traffic congestion is annoying, but there must be some advantages to driving on that crowded road or pe
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