1 Never use a microwave or conventional oven to pre-heat your flask. 2  If your flask has not been used for some time, rinse with warm water to remove any residual odours.  DO NOT overfill your flask. Leave sufficient space in the neck to fit the stopper.
Prevalence is a measure of disease that allows us to determine a person's likelihood of having a disease. Therefore, the number of prevalent cases is the total number of cases of disease existing in a population.
Period prevalence is the proportion of a population that has the characteristic at any point during a given time period of interest. âPast 12 monthsâ is a commonly used timeframe. Lifetime prevalence is the proportion of a population who, at some point in life up to the time of assessment, has ever had the characteristic.