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Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Dis cus si on Papers are inten ded to make results of ZEW research prompt ly avai la ble to other eco no mists in order to encou ra ge dis cus si on and sug gesti ons for revi si ons. The aut hors are sole ly respon si ble for the con tents which do not neces sa ri ly repre sent the opi ni on of the ZEW. Terms of use: Documents in EconStor mayDownload this ZEW Discussion Paper from our ftp server:http://ftp.zew.de/pub/zew-docs/dp/dp12012.pdf Non-technical SummaryThe study of the innovative output of firms often relies on a count of patents filed at one single patent office, although companies have the option to file patents at multiple offices such as their national patent office, the European Patent office (EPO), the World Intellectual Property Office, the US Patent and Trademark Office, or in any other jurisdiction. In Europe, the office of reference used is often the EPO. Yet, not all firms file their patents at the EPO, raising the specter of a selection bias.Motivated by the tension between the popularity of the single office count and the threat of a selection bias, the objective of this paper is twofold. First, we study whether the single-office count biases econometric estimates of innovation production functions.Innovation production functions, which relate a firm's inventive input to its output, are a key object of analysis in the innovation literature. Second, we propose a simple way to test the existence of bias when the econometrician observes patents at only one patent office.The analysis is performed on a panel of Belgian patenting firms. Three databases are We show that the single-office count results in a selection bias that affects econometric estimates of innovation production functions. In addition, we demonstrate the usefulness of our test to evaluate whether estimates that rely on the single-office count are affected by a selection bias. The test, which uses information that is readily available to most researchers, successfully spots variables that are subject to a selection bias. It should be of interest to a wide audience given its ease of use and the popularity of the single-office count among innovation scholars. Das Wichtigste in Kürze December 2011 AbstractThe study of the innovative output of firms often relies on a count of patents filed at one single office of reference such as the European Patent Office (EPO). Yet, not all firms file their patents at the EPO, raising the specter of a selection bias. Using a novel dataset ...

Die Dis cus si on Pape rs die nen einer mög lichst schnel len Ver brei tung von neue ren For schungs arbei ten des ZEW. Die Bei trä ge lie gen in allei ni ger Ver ant wor tung der Auto ren und stel len nicht not wen di ger wei se die Mei nung des ZEW dar.Dis cus si on Papers are inten ded to make results of ZEW research prompt ly avai la ble to other eco no mists in order to encou ra ge dis cus si on and sug gesti ons for revi si ons. The aut hors are sole ly respon si ble for the con tents which do not neces sa ri ly repre sent the opi ni on of the ZEW.Download this ZEW Discussion Paper from our ftp server:http://ftp.zew.de/pub/zew-docs/dp/dp12012.pdf Non-technical SummaryThe study of the innovative output of firms often relies on a count of patents filed at one single patent office, although companies have the option to file patents at multiple offices such as their national patent office, the European Patent office (EPO), the World Intellectual Property Office, the US Patent and Trademark Office, or in any other jurisdiction. In Europe, the office of reference used is often the EPO. Yet, not all firms file their patents at the EPO, raising the specter of a selection bias.Motivated by the tension between the popularity of the single office count and the threat of a selection bias, the objective of this paper is twofold. First, we study whether the single-office count biases econometric estimates of innovation production functions.Innovation production functions, which relate a firm's inventive input to its output, are a key object of analysis in the innovation literature. Second, we propose a simple way to test the existence of bias when the econometrician observes patents at only one patent office.The analysis is performed on a panel of Belgian patenting firms. Three databases are We show that the single-office count results in a selection bias that affects econometric estimates of innovation production functions. In addition, we demonstrate the usefulness of our test to evaluate whether estimates that rely on the single-office count are affected by a selection bias. The test, which uses information that is readily available to most researchers, successfully spots variables that are subject to a selection bias. It should be of interest to a wide audience given its ease of use and the popularity of the single-office count among innovation scholars. Das Wichtigste in Kürze December 2011 AbstractThe study of the innovative output of firms often relies on a count of patents filed at one single office of reference such as the European Patent Office (EPO). Yet, not all firms file their patents at the EPO, raising the specter of a selection bias. Using a novel dataset of the whole population of patents by Belgian firms, we show that the singleoffice count results in a selection bias that affects econometric estimates of innovation production functions. We propose a methodology to evaluate whether estimates that rely on the singleoffice count are affected by a selection bias. JEL Codes: O31, C18, C52, C81