The cause of an acute exacerbation is usually unknown, although some acute exacerbations result from bacterial or viral infections. Smoking, irritative inhalational exposure, and high levels of air pollution also contribute.
Operational Definition. The operational definition of a variable is the specific way in which it is measured in that study. Another study might measure the same conceptual measure differently.If you were studying ways of helping people stop smoking, smoking cessation would be an outcome measure (dependent variable).ou could measure smoking cessation as a person not smoking a cigarette for 1 month, or as a person who has not smoked in a year, or a 50% reduction in the number of cigarettes smoked. Clearly the operational definition of the dependent variable is an important step in the design of the study.
An operational definition is a detailed specification of how one would go about measuring a given variable. Operational definitions can range from very simple and straightforward to quite complex, depending on the nature of the variable and the needs of the researcher. Operational definitions should be tied to the theoretical constructs under study. The theory behind the research often clarifies the nature of the variables involved and, therefore, would guide the development of operational definitions that would tap the critical variables.