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Re: st: Fraud methods in Stata


From   Ronan Conroy <rconroy@rcsi.ie>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Fraud methods in Stata
Date   Sat, 27 Sep 2008 14:19:51 +0100

On 26 Sep 2008, at 16:20, Williams, Rachael wrote:

If anyone has any ideas of other ways to detect possible fraud I would
love to hear from you too!
Having been peripherally involved in a case of academic fraud, there are two interesting tendencies that people show when inventing data:

1. They do not understand random variability. Typically, invented data has a smaller dispersion than real data, and the distribution tends to be uniform rather than normal. People often confuse 'random' with 'evenly distributed'. In particular, differences between measurements supposedly taken on different occasions has a very narrow distribution.
2. The previous observation influences the value if the person is inventing data at the keyboard. They try to make each observation different, causing a correlation between the values for adjacent observations.

In addition, watch out for data organised in a way that makes it hard to transcribe from the written source but easy to enter on a computer. In this case, instead of all the pretest items from a questionnaire being entered, followed by the post-test items, each item was entered with the pretest and post-test values in adjacent columns. Clearly, this would be hopelessly inefficient if you really had the questionnaires, but easy if you were inventing the data to show pretest-posttest differences.


Ronan Conroy
=================================

rconroy@rcsi.ie
Royal College of Surgeons in Ireland
Epidemiology Department,
Beaux Lane House, Dublin 2, Ireland
+353 (0)1 402 2431
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http://www.flickr.com/photos/ronanconroy/sets/72157601895416740/

P Before printing, think about the environment




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