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.
The operational definition also helps to control the variable by making the measurement constant. Therefore, when it comes to operational definitions of a variable, the more detailed the definition is, the better. For example, if the researcher was planning to weigh research subjects, there would several constructs that should be spelled out including what the subjects were to wear, whether or not they would wear shoes, what type of scale was being used, and time of day.