involves two parties: the person or organization that originally collected the data and the person or organization that would like to make use of an existing data source.² Disincentives exist for both (Natriello, 2003).

For individual researchers who have engaged in data collection, it is not always clear how to prepare data to share, a problem that has intensified as data sets have become more complex. A further disincentive along this line is that the process of preparing data to be shared requires considerable effort (and therefore cost) beyond what is required for preparing data for analysis and publication. A lack of standards for the preparation and archiving of public data sets leads to institutions and individuals having to reinvent the wheel in determining how to go about the process of data preparation. Finally, researchers may be reluctant to share their data because when they do so, they lose exclusivity for reporting on the data. Researchers often want to hold their data as long as possible so that they have the advantage in analyzing them before the larger community gains access to them (Natriello, 2003).

There are also disincentives for researchers who want to use existing data. Such efforts often require researchers to expend considerable effort (and therefore cost) in order to overcome technical barriers. Some researchers do not view the work as truly their own if they were not involved in the data collection. Finally, publication outlets can serve as a significant disincentive for conducting work using existing data. Peer-reviewed journals as well as tenure and promotion policies both tend to value publications that strike off in new directions or provide novel ideas and to devalue studies that build on previous work (Schneider, 2003; Natriello, 2003).

These and related issues will need to be addressed formally to mitigate such disincentives. For example, universities and departments could work to change tenure and promotion decisions so that they recognize efforts that promote data sharing as valuable intellectual contributions to the field; a singular focus on rewarding researchers for publishing in a small set of elite journals may not serve the field in the long run. Associations could lead an effort to develop standards and protocols for preparing data to be shared. And federal funding agencies could encourage the sharing of data by outlining the conditions under which it is permissible in the informa-