  An initial motivation behind Stotz and Griffith's project was to test philosophical accounts of the gene concept. As Griffiths asked, if their survey-based study revealed that scientists don't actually think of genes in the way set out by a philosophical account, then what value could the account possibly have? There are, however, a number of daunting, practical difficulties with using a questionnaire to learn how a person is thinking, especially if the person's thinking involves the use of multiple concepts and/or is sometimes or somewhat muddled (Waters 2004b). It is also difficult to survey appropriate and representative samples of scientists. Griffiths and Stotz are aware of these difficulties and have refined their project through successive surveys.