internet piracy and book sales

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  • Internet piracy and book sales. A field experiment.

    Wojciech Hardy

    Micha Krawczyk

    EEA 2015

    Joanna Tyrowicz

    Group for Research in APplied Economics

  • Summary of the results

    Book industry representatives concern about internet piracy might be exaggerated.

    (At least) for now.



  • Many studies for film and music industries.

    Mixed results depending on: The methodology.

    The analyzed good.

    The analyzed period.

    A few studies on book industry. But: Small-scale (almost case studies).

    Specific genres of books.

    Not really on piracy.


    Design Recruitment Literature Matching Treatment

    Main problems:

    Seasonal effects


    Omitted variable

    Perfect tool? Experiments!

  • In general The sample should be:

    Large (for statistical inference).

    Varied (for representativeness).

    Long (to control for seasonal effects).

    The experimental methodology would deal with: Reverse causality (a reference group).

    Omitted variables (randomized treatment application).

    In detail Acquire book data.

    Match them in groups (two or more books as similar as possible!).

    Protect one randomly chosen book in each pair.

    Do it for a year.

    Compare the two outcomes.


    Design Recruitment Literature Matching Treatment

    Contribution? New industry

    New methodology New conclusions

  • Around 70 Polish publishers contacted.

    11 accepted.

    9 went through with providing all of the data

    Data on 249 titles for over a year

    Different genres: legal, business, linguistic, fiction, fantasy, etc.

    Both medium and larger publishers,

    Both popular and niche titles


    Design Recruitment Literature Matching Treatment

  • We split them into matched pairs (groups)

    The variables they are matched on: Publication date & edition

    Page count

    Versions available (type of cover, digital)

    Sales forecasts (monthly)

    Number of unauthorized copies found prior to the experiment

    Matching results: Groups of two: 94

    Groups of three: 13

    Groups of five: 1


    Design Recruitment Literature Matching Treatment

  • Within each group we have randomly picked protected and control titles.

    Thus both groups were comparable.

    We did nothing to the Control Treatment (CT) group.

    Agency removed unauthorized copies from the Enforcement Treatment (ET) group.

    We observed both groups between 11.2012 and 9.2013.


    Design Recruitment Literature Matching Treatment

    A note on file-sharing in Poland.

    Alexa ranking of

    most popular websites: 17th

    Pirate Bay 66th

  • 1) Data from

    2) Counterfactual excercise: searched for 20 titles each (RAs).

    Found fewer protected books.

    If found searched longer.

    If found mostly non-standard sources.


    Manipulation check

  • We received sales data.

    Some distribution.

    They could be negative (what we did)

    Smth by genre?


    Sales data

  • Experimental data, no need for regressions

    No difference in sales, or variance



  • 11


  • Lets recheck our strategy and add controls.

    No results!


    Regressions if heterogeneity

  • Popularity? (see this and that)

    No results!


    Regressions if distributional effects

  • Good thing about piracy that you dont need a result



    We have performed a large field experiment on piracys impact on book sales. We applied a robust methodology and checked for more complex relationships. Internet piracy does not seem to pose a threat to the book industry. Of course, the situation is likely to evolve quickly.

  • Thank you for your attention! Author: Joanna Tyrowicz e-mail:

    More about our research on

    Twitter: @GrapeUW