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.
For example, self-esteem is a measure of how people feel about themselves. The OPERATIONAL DEFINITION provides a concrete description of the variable. directly measured. In addition, whether or not the variable can be directly measured, the operational definition names the possible values of the variable.