Epidemiology module of practical skills for mbbs student

Types

a. Crude Rates: birth and death rates. These are un-standardized rates.

b. Specific rates: disease specific, age and sex specific, time specific.

c. Standardized rates: these are obtained by direct or indirect method of standardization or adjustment e.g. age and sex standardized rates.

2. 
   Ratio:
   

It expresses a relation in size between two random quantities. The numerator is not a component of denominator. The numerator and denominator may involve an interval of time or may be instantaneous in time. Broadly, ratio is the result of dividing one quantity by another. It is expressed in the form of x: y, e.g. sex ratio, doctor-population ratio, child-woman ratio, etc.

Say sex ratio is 933: 1000.

3. 
   Proportion:
   

is a ratio, which indicates the relation in magnitude, of a part to the whole. The numerator is always included in the denominator. It is usually expressed in percentage, e.g. percent of under five children suffering from malnutrition of the total under five populations. Say a proportion of 60% of the under five children is suffering from malnutrition.