How much of the decline in sound recording sales is due to file-sharing?

Although most studies of file-sharing have concluded that file-sharing has decreased record sales, the extent of the decreased sales often seems uneven. This paper demonstrates that the results are more uniform than previously understood once a consistent metric is used to provide easy comparability across studies. This paper uses the percent of the decline in record sales that is due to file-sharing as a metric to translate the results of the literature into a common framework and then summarizes those results. What has not been previously noted is that the estimates from most studies imply that the impact of file-sharing was sufficient to have caused the entire decline in record sales that occurred from the advent of Napster up to about 2005. A smaller number of studies using post-2005 data indicate that the shift to digital formats may also have contributed to the sales decline that continued after 2005.