Extracting data from graphs for systematic review/meta analy

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srlb2
Posts: 125
Joined: Mon Feb 27, 2012 6:43 pm

Extracting data from graphs for systematic review/meta analy

Post by srlb2 » Mon Jan 06, 2014 4:57 pm

Hi everyone,

As part of my PhD I'm doing a meta analysis of intervention research however a lot of the studies only give data in graphs with some or no corresponding numbers in the text or in tables. Due to the sheer number of studies that do this it might not be feasible to contact all of the authors to obtain the data as some studies are very old (so the researchers might not still have the data) and many may not reply or have changed correspondence details.

One of my supervisors suggested extracting data from the graphs but I have no experience of doing this. He said the common practice is to enlarge the graph and work out the data points from this. Does anyone have any experience of doing this? I'm completely lost and confused as it seems like a very inaccurate way to extract data but I could be missing something!

Thanks!

Srlb2

srlb2
Posts: 125
Joined: Mon Feb 27, 2012 6:43 pm

Post by srlb2 » Sat Mar 08, 2014 1:06 pm

Just replying in case anyone else ever needs this question answered! I've discovered that there are literally hundreds of free or very cheap software packages out there which can extract data from graphs either automatically or with the user clicking each individual point. I've tested the accuracy of a few and found GetData to be the easiest to use and most accurate. It also has the best features as it allows you to extract multiple lines on the same graph and save the output. It costs around £23 :-)

Srlb2

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Alexander
Posts: 292
Joined: Tue Aug 04, 2009 11:19 pm

Re: Extracting data from graphs for systematic review/meta a

Post by Alexander » Mon Mar 10, 2014 8:49 am

Thanks for the update. Useful to know.

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