Although different populations may require slightly different assessment instruments, a basic symptom assessment scale that has an adequate sampling of symptoms, and applicable to all patients with cancer, should be utilized so the symptom cluster findings can lead to consistent data analysis. The analytical methods most commonly used are cluster analysis and factor analysis. The choice of method, however, depends upon the study objectives, underlying assumptions and method of symptom assessment. Both cluster analysis and factor analysis are exploratory techniques that are intended to reveal the underlying structure of data. Although factor analysis tends to be used with group variables and cluster analysis tends to be used with groups of individuals,20 the two methods can be used interchangeable.21