{"id":161,"date":"2023-08-03T18:24:18","date_gmt":"2023-08-03T18:24:18","guid":{"rendered":"https:\/\/ozer.gt\/log\/?p=161"},"modified":"2024-01-27T07:33:38","modified_gmt":"2024-01-27T07:33:38","slug":"what-if-parallel-trends-are-not-so-parallel","status":"publish","type":"post","link":"https:\/\/ozer.gt\/log\/2023\/08\/03\/what-if-parallel-trends-are-not-so-parallel\/","title":{"rendered":"What if parallel trends are not so parallel?"},"content":{"rendered":"

In Data Duets, Duygu Dagli<\/a> and I offered our take on Ashesh Rambachan<\/a> and Jonathan Roth<\/a>‘s recently published but long overdue paper now titled “A more credible approach to parallel trends.”<\/p>\n

Problem:
\nWe want to test the causal effect of a promotion on sales, let’s say a coupon. The coupon was sent to newer customers. Did the coupon increase the sales? Or would the new customers have bought more anyway?<\/p>\n

Solution:
\nWe’ll never know the answer to the last question but we can answer the first question after making some assumptions. More on this in the post.<\/p>\n

This is less elaborate than our earlier posts on synthetic controls and Lord’s paradox. We will probably keep it this way so that we can post more often.<\/p>\n

Source<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

In Data Duets, Duygu Dagli and I offered our take on Ashesh Rambachan and Jonathan Roth‘s recently published but long overdue paper now titled “A more credible approach to parallel trends.” Problem: We want to test the causal effect of a promotion on sales, let’s say a coupon. The coupon was sent to newer customers. […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"cybocfi_hide_featured_image":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-161","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/posts\/161","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/comments?post=161"}],"version-history":[{"count":1,"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/posts\/161\/revisions"}],"predecessor-version":[{"id":162,"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/posts\/161\/revisions\/162"}],"wp:attachment":[{"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/media?parent=161"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/categories?post=161"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ozer.gt\/log\/wp-json\/wp\/v2\/tags?post=161"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}