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EPIDEMIOLOGY Watching
“EPIDEMIOLOGY watching” is a forum to address broad aspects of epidemiologic research – its history, its methods, its impact – and to stimulate discussion among its students and practitioners.
Wednesday, December 08, 2010
A TIDBIT by Jay Kaufman
As I mentioned in the editorial announcing this blog, I am open to ideas, great and small to blog about. This is one volunteered by Jay Kaufman:
 
“DataThief”
 
“DataThief III is a program to extract (reverse engineer) data points from a graph.  Typically, you scan a graph from a publication, load it into DataThief, and save the resulting coordinates, so you can use them in calculations or graphs that include your own data.”  [from the link]
 
What a nifty idea!  For many teaching examples, we’d like to analyze data presented in graphs and figures. It can be a painstaking process to read the data points off of the image, especially if the type is small or the resolution poor. We asked a colleague to do a validation run of test cases (where the original data were available). He reports that, while not completely user-friendly (getting the marker exactly on the data point isn't easy), the answers on a test case with known values were within rounding error. With some effort this could really come in handy.
 
 
Jan P Vandenbroucke
 
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12/8/2010
blog reader said:
Arnout Standaert writes: The idea of using software to digitize published data is pretty old, and several software packages exist. It’s indeed a great idea to improve the accuracy and availability of background information in research. One thing that slightly bothers me is the mentioned software, Data Thief. Research should be an open process, relying on transparency, open standards, and open tools. That includes open source software. While Data Thief is without a doubt a useful piece of software, it is shareware and usage is prohibited without payment. However, there are perfectly fine open source alternatives. One that I have used myself and appreciate is Engauge Digitizer, available at http://digitizer.sourceforge.net/. It would benefit an open science process to promote not only commercial tools, but also the open source alternatives. This not only allows everyone to enjoy the benefits without cost, it also allows anyone to contribute to the tools and improve them as desired.
About the Author

Jan P. Vandenbroucke
Jan P. Vandenbroucke is a professor of Clinical Epidemiology at Leiden University and an Academy Professor of the Royal Netherlands Academy of Arts and Sciences. He studied medicine in Belgium and epidemiology at Harvard. He serves on the advisory board of The Lancet, is co-editor of the James Lind Library and the People’s Epidemiologic Library, and is co-author of the STROBE guidelines (Strengthening the Reporting of Observational Studies in Epidemiology).

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