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MEASURING THE EFFECT OF NAPSTER ON RECORDED MUSIC SALES: DIFFERENCE‐IN‐DIFFERENCES ESTIMATES UNDER COMPOSITIONAL CHANGES
Author(s) -
Hong SeungHyun
Publication year - 2013
Publication title -
journal of applied econometrics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.878
H-Index - 99
eISSN - 1099-1255
pISSN - 0883-7252
DOI - 10.1002/jae.1269
Subject(s) - estimator , matching (statistics) , econometrics , difference in differences , the internet , propensity score matching , advertising , economics , business , computer science , statistics , mathematics , world wide web
SUMMARY This paper measures the effect of Napster on record sales. I treat the introduction of Napster as a technological event that only Internet users experienced, and use a difference‐in‐differences (DD) approach. Because of potential compositional changes in Internet users, I examine identifying assumptions for the DD estimator under compositional changes and develop a test for identifying restrictions. To address potential bias due to compositional changes, I extend DD matching estimators to the case of two‐variate propensity scores. I find evidence suggesting that file sharing is likely to explain 20% of total sales decline, which is driven by households with children aged 6–17. Copyright © 2011 John Wiley & Sons, Ltd.