The main use of the Neuman Model in practice and in research is that its concentric layers allow for a simple classification of how severe a problem is. For example, since the line of normal defense represents dynamic balance, it represents homeostasis, and thus a lack of stress. If a stress response is perceived by the patient or assessed by the nurse, then there has been an invasion of the normal line of defense and a major contraction of the flexible line of defense. Infection or other invasion of the lines of resistance indicates failure of both lines of defense. Thus, the level of insult can be quantified allowing for graduated interventions. Furthermore each person variable can be operationalized and the relationship to the normal line of defense or stress response can be analyzed. The drawback of this is that there is no way to know whether our operationalization of the person variables is a good representation of the underlying theoretical structures.

For example, Eileen Gigliotti published a research article in 1999 based on the Neuman Systems Model. The study investigated the relationship of multiple role stress to the psychological and sociocultural variables of the flexible line of defense. If multiple role stress had occurred, then the normal line of defense had been invaded. Questionnaire instruments were used to operationalize the psychological component with perceived role as a student and as a mother; the sociocultural component with social support, the normal line of defense as perceived multiple role stress.

Upon analysis, no conclusions could be made about the normal line of defense simply on the basis of the psychological component and sociocultural component. By dichotomizing the data by median age, however, a relationship between them could be described. Thus the relationship between the normal line of defense and the psychological and sociocultural components could only be described by taking into account the developmental component. It indicates that the components of the flexible line of defense interact in very complex ways and it may be difficult and dangerous to overgeneralize their interaction.