{"id":1315,"date":"2014-11-16T16:26:08","date_gmt":"2014-11-16T23:26:08","guid":{"rendered":"http:\/\/www.mii.ucla.edu\/causality\/?p=1315"},"modified":"2014-11-16T16:26:08","modified_gmt":"2014-11-16T23:26:08","slug":"on-dags-instruments-and-social-networks","status":"publish","type":"post","link":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/2014\/11\/16\/on-dags-instruments-and-social-networks\/","title":{"rendered":"On DAGs, Instruments and Social Networks"},"content":{"rendered":"<p>Apropos the lively discussion we have had here on graphs and IV models, Felix Elwert writes:<\/p>\n<p>&#8220;Dear Judea, here&#8217;s an <a href='http:\/\/causality.cs.ucla.edu\/blog\/wp-content\/uploads\/2014\/11\/omalley_elwert1.pdf'>IV paper using DAGs <\/a>that we recently published. We use DAGs to evaluate genes as instrumental variables for causal peer effects in social networks. The substantive question is whether obesity is contagious among friends. We evaluated both single-IV and IV-set candidates. We found DAGs especially helpful for evaluating variations within a large class of qualitative data-generating processes by playing through a lots of increasingly realistic variations of our main DGPs (Table 1). Being able to discuss identification purely in terms of qualitative causal statements (e.g., &#8220;fat genes may affect latent causes of friendship formation&#8221;) was very helpful. One of our goals was to check far one can relax the DGP before identification would break down. After permitting a host of potential hurdles (i.e., eliminating exclusions left and right by drawing lots of additional arrows), we concluded that genes alone won&#8217;t realistically work, but that time-varying gene expression might give valid IVs for peer effects. Under linearity, we found suggestive evidence for the transmission of obesity in social networks.&#8221; <\/p>\n<p>All the best,<\/p>\n<p>Felix<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Apropos the lively discussion we have had here on graphs and IV models, Felix Elwert writes: &#8220;Dear Judea, here&#8217;s an IV paper using DAGs that we recently published. We use DAGs to evaluate genes as instrumental variables for causal peer effects in social networks. The substantive question is whether obesity is contagious among friends. We [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-1315","post","type-post","status-publish","format-standard","hentry","category-general"],"_links":{"self":[{"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/posts\/1315","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=1315"}],"version-history":[{"count":0,"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/posts\/1315\/revisions"}],"wp:attachment":[{"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=1315"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/categories?post=1315"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/causality.cs.ucla.edu\/blog\/index.php\/wp-json\/wp\/v2\/tags?post=1315"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}