andrew_gelman_stats andrew_gelman_stats-2013 andrew_gelman_stats-2013-2142 knowledge-graph by maker-knowledge-mining
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Introduction: Fabio Rojas writes : After reading the Fowler/Christakis paper on networks and obesity , a student asked why it was that friends had a stronger influence on spouses. In other words, if we believe the F&C; paper, they report that your friends (57%) are more likely to transmit obesity than your spouse (37%) (see page 370). This might be interpreted in two ways. First, it might be seen as a counter argument. This might really indicate that homophily is at work. We probably select spouses for some traits that are not self-similar. While we choose friends mainly on self-similarity of leisure and consumption (e.g, diet and exercise). Second, there might be an explanation based on transmission. We choose friends because we want them to influence us, while spouses are (supposed?) to accept us. Your thoughts? My thought: No. No no no no no. No no no. No. From the linked paper: A person’s chances of becoming obese increased by 57% (95% confidence interval [CI], 6 to 123) if h
sentIndex sentText sentNum sentScore
1 Fabio Rojas writes : After reading the Fowler/Christakis paper on networks and obesity , a student asked why it was that friends had a stronger influence on spouses. [sent-1, score-0.476]
2 In other words, if we believe the F&C; paper, they report that your friends (57%) are more likely to transmit obesity than your spouse (37%) (see page 370). [sent-2, score-0.46]
3 We probably select spouses for some traits that are not self-similar. [sent-6, score-0.202]
4 We choose friends because we want them to influence us, while spouses are (supposed? [sent-10, score-0.43]
5 From the linked paper: A person’s chances of becoming obese increased by 57% (95% confidence interval [CI], 6 to 123) if he or she had a friend who became obese in a given interval. [sent-17, score-0.74]
6 If one spouse became obese, the likelihood that the other spouse would become obese increased by 37% (95% CI, 7 to 73). [sent-21, score-0.633]
7 The mistake made by Rojas’s student is to overinterpret chance variation. [sent-28, score-0.304]
8 Amy sinks 6 out of 20 shots, and Beth sinks 4 out of 20. [sent-32, score-0.254]
9 The difference could easily, easily be explained by chance. [sent-41, score-0.176]
10 It’s not that any of these (hypothetical) explanations are necessarily wrong —indeed, they could all be true, it could be that Amy’s family is more supportive and that Beth was under more pressure etc etc—but there’s essentially no evidence to support them. [sent-42, score-0.722]
11 The explanations could just have well been made before any shots were even taken. [sent-43, score-0.465]
12 The trouble is that they’re being used to explain a pattern that could well be noise. [sent-47, score-0.248]
13 It still could be a useful exercise: first explain pattern A, then explain pattern not-A. [sent-48, score-0.42]
14 Even if you completely accept the framework of the published research and don’t worry about any selection effects, you’re comparing the confidence interval [6, 123] to the interval [7, 73]. [sent-51, score-0.337]
15 This is just a good opportunity to bring up an issue that occurs a lot in social science: lots of theorizing to explain natural fluctuations that occur in a random sample. [sent-56, score-0.191]
16 ) The point here is not that some anonymous student made a mistake but rather that this is a mistake that gets made by researchers, journalists, and the general public all the time. [sent-58, score-0.443]
17 Just remember that if, as is here, the data are equivocal, that it would be just as valuable to give explanations that go in the opposite direction. [sent-60, score-0.231]
18 The data here are completely consistent with the alternative hypothesis that people follow their spouses more than their friends when it comes to obesity. [sent-61, score-0.374]
19 I checked back on Rojas’s post and, scarily enough, two of the three comments offer potential explanations for the difference, with neither commenter seeming to realize that they are chasing noise. [sent-64, score-0.435]
20 Again, there’s nothing wrong with theorizing but I think it’s helpful to realize that these are pure speculations with essentially no basis in data, so one could just as well be giving explanations for why the underlying difference goes in the opposite direction. [sent-65, score-0.744]
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Introduction: Fabio Rojas writes : After reading the Fowler/Christakis paper on networks and obesity , a student asked why it was that friends had a stronger influence on spouses. In other words, if we believe the F&C; paper, they report that your friends (57%) are more likely to transmit obesity than your spouse (37%) (see page 370). This might be interpreted in two ways. First, it might be seen as a counter argument. This might really indicate that homophily is at work. We probably select spouses for some traits that are not self-similar. While we choose friends mainly on self-similarity of leisure and consumption (e.g, diet and exercise). Second, there might be an explanation based on transmission. We choose friends because we want them to influence us, while spouses are (supposed?) to accept us. Your thoughts? My thought: No. No no no no no. No no no. No. From the linked paper: A person’s chances of becoming obese increased by 57% (95% confidence interval [CI], 6 to 123) if h
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