Background: The use of probability sampling is the benchmark of survey research as it increases the likelihood of obtaining results which can be generalised. However, fleeting attention has been given to using a probability sample drawn from professional associations; in this instance, nurses who belong to particular specialty groups. Currently, there is little research which has highlighted sample differences within a specific target population associated with the use of two different sampling approaches in one study. Objective: This paper presents a secondary analysis of the results of an Australian study that measured general self-efficacy, perceived competence, trait hope, peer support, collaboration with medical staff, cohesion among nurses, managing stress, planful coping, and resilience in two samples of operating room nurses. The first sample was drawn using systematic random sampling from a professional association, and the second was drawn using a purposive sample of hospital nurses to illustrate significant differences in demographic characteristics and scale scores across these two samples. Methods: The target population of this study included all operating roomnurses practising in this speciality in all Australia states and territories. Based on this, two accessible populations were delineated. The association sample (n = 772) was randomly drawn from a national association of Australian operating room nurses, whilst the hospital sample (n = 124) consisted of all operating room nurses from two large tertiary hospitals in Queensland, Australia. Results: Significant differences between the association and hospital samples were identified. Nurses in the association sample were older, more experienced and a considerably higher proportion of nurses in this sample possessed specialty qualifications than their counterparts in the hospital sample (p < 0.0001). Additionally, there were differences between these two samples in seven out of the nine scales used in this study. Conclusions: In this study, the use of a professional specialty association allowed a national random sample; nevertheless, this sample was not similar to the operating room nurses practising in one state. However, detection of such differencesmay not have been apparent if one sampling method had been used exclusively. The results of this study highlight the context that local level purposive samples add to information gained through probability sampling of large national broader level contexts.