McMaster University

Graduate Program in Statistics



STATISTICS SEMINAR



SPEAKER:
Noori Akhtar-Danesh
Department of Nursing
Faculty of Health Science
McMaster University
Date :Wednesday April 2, 2003.
Time : 3:30pm
Address Burke Science Building
Room: 138
TITLE:
How Does Correlation Structure Differ Betweem Real Data-sets and Made-up (fabricated) Data-sets?
ABSTRACT:
Misconduct in medical research has been subject of many papers in recent years. Some types of fraud which have been reported are data fabrication and data falsification, plagiarism, deceptive reporting of results, suppression of existing data, and deceptive design or analysis.

In this presentation we emphasize on one extreme case of fraud; data fabrication. Our main objective is to find out how closely the correlation structures could be reconstructed by fabricated data. In order to investigate the correlation structures of fabricated data-sets, the summary statistics of two real data-sets were shown to faculty members at two medical schools and they were asked to make-up similar data-sets on their own. In the first example we considered two variables which were highly correlated; the height and the weight of 65 female students aged 19-22 (r = 0.43). The correlation coefficient for the 34 made-up data-sets ranged from -0.097 to 0.996. Most participants produced correlation coefficient greater than that of the real data-set. In the second example we considered two variables which were not correlated; the gestational ages (GA) and the weights of 637 newborn boys (r = 0.031). Each participant was asked to write down GA and weight for 40 babies in the ranges of the real data-set. The correlations between GA and weight for the 34 collected fabricated data-sets were in the range of -0.36 to 0.98. In conclusion made-up data-sets yield considerably higher correlation coefficients than the corresponding real data-sets.

This is joint work with Mahshid Dehghan-Kooshkghazi.

About the Speaker
Dr Akhtar-Danesh is an assistant professor in the School of Nursing, at McMaster University. He received his PhD in (Medical) Statistics from the University of Newcastle Upon Tyne, UK (1997). He did his PhD on evaluating different methods of analyzing postoperative pain measures. His research interests include methods of analyzing pain measurements, structure of fabricated data sets, longitudinal data and repeated measures, missing data, and multivariate analysis. During his previous careers he designed many clinical trials and observational studies for faculty members and postgraduate students, supervised MSc students on their theses, and taught statistical and epidemiological courses to undergraduate and postgraduate students.
References
Some relevant background references will be posted here shortly.


Department of Mathematics and Statistics
Graduate Program in Statistics

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Last updated on April 1, 2003