There are many different strategies for collecting data: experiments, simulations, participant observation, case studies, focus groups, survey research, analysis of archival data, and content analysis are leading examples. A combination of strategies is sometimes advisable because multitrait, multimethod analysis can be more valid than monistic approaches. That is, having multiple measures of each concept, measured multiple ways, may lead to valid results more than single measurements taken through one strategy. For example, using focus groups to back up survey questionnaire data or case studies to back up statistical analysis of archival data are common combinations of data gathering strategies.