September 2, 2005 Source: University of Waterloo: https://lists.uwaterloo.ca/pipermail/uw-news-release/2005-September/000455.html UW Survey Research Centre examines outcomes WATERLOO, Ont. -- Survey says . . . When we answer a survey or read the results of one, we assume that the results tell us something about relationships and casual connections. For instance, if a survey about reactions to graphic warning labels on cigarette packages found that after 10 years of nasty smoking labels fewer people were still smoking, it might be an indication that the labels work. Or would it? Prof. Mary Thompson, co-director of the University of Waterloo Survey Research Centre, devotes some of her research to the extraction of meaning from surveys. "There is a great deal of scope for using surveys to observe processes and to see how one kind of event leads to another, but the surveys have to be designed appropriately to examine supposed relationships and connections," she said. Thompson, of the Department of Statistics and Actuarial Science, is particularly interested in longitudinal studies -- where observations of individuals are made several times, typically over the course of years. A longitudinal study gives the researchers snapshot pictures of a population as time progresses. But there can be fairly significant problems in interpreting the results. "Every study has dropout, but if you are sampling over a long time the dropout rate may be pronounced. Do you replenish the sample, and if so, how is this done to make the best use of continuing respondents and new recruits, who may be statistically quite different? These decisions need to be made in the design of the sampling scheme and are key to the success of a longitudinal survey." Thompson is working on a survey, developed by UW Prof. Geoff Fong of Psychology and other colleagues, of smokers and their responses to anti-smoking measures such as graphic labels. She applies mathematical and statistical theory to the design of this kind of population health survey. "The researchers who conceived the study are psychologists and health scientists concerned with whether this type of action is effective. My role is to try to ensure that their results can help to answer the research questions," she said. The role of the statistician is often to model error or noise so that it is easier to see the patterns that are sometimes hidden in mountains of data. "One fundamental technique is to try to find patterns in multi-dimensional data by reducing the dimensions," Thompson said. "Sometimes that is a straightforward process, as in many engineering applications, but with data from human respondents it can be harder to find discernible patterns and appropriate reductions of dimensionality. The role of theory is very important and designing and administering a survey carefully may shed light on parts of the structure and allow us to see that changes in one variable might have tremendous effects on another." As well, observing systems "without taking proper account of noise and randomness can lead you astray and make you misinterpret results," she said. "But, through careful mathematical modeling of the randomness, you can look at the phenomenon and make sense of the uncertainty." Thompson's research is the kind that allows science, engineering and the social sciences to make tremendous breakthroughs. "I don't think of what I am doing as being very 'gee-whiz.' because by its very nature it has to be abstract. "But the statistician's role in science through probabilistic modelling is crucial. In a sense that role is to develop the abstractions which support the inferences underlying those remarkable discoveries," Thompson explained. (Written by Graeme Stemp, SPARK -- Students Promoting Awareness of Research Knowledge -- writing program.) -30- Contact: Prof. Mary Thompson, (519) 888-4567, ext. 5543; methomps at uwaterloo.ca Jim Fox, UW Media Relations, (519) 888-4444; jfox at uwaterloo.ca Release no. 196 -- September 2, 2005
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