Tutorial :4 Variable classification according to their nature

Variable classification according to their nature

a. Independent variables

Variables, which are either manipulated by the researcher, or variables, which cannot be controlled by the study but will affect the results of the study, are called independent variables. Age can be independent variable under study, which may affect the outcome variable such as survival in days etc

b. Dependent variables

The outcome variables under the research problem are called as dependent variables and they will be affected by the independent variables under study. The outcome variables such as no of people developed a particular disease in a cohort study

Variable classification according to their type

a. Quantitative variables

Variables, which can be measured numerically, are called quantitative variables. These variables can be further classified as continuous and discrete variables A continuous variable could take any value in an interval Examples of continuous data are body mass, height, blood pressure, and cholesterol.

Discrete variables will whole integer values. Example: number of needle punctures and number of hospitalizations


b. Qualitative variables
Variables, which cannot be measured numerically, are called qualitative variables.

Variable classification according to the scale of measurement

a. Nominal Scale variables

These variables, which are using nominal scale of measurements, can only be classified and cannot be ordered and not suitable for mathematical treatments. Variables such as gender, name etc.

b. Ordinal Scale Variables

These variables can be ordered. However, the intervals between the numbers are not necessarily equal.

Example: Star Rating for Institutions, (Institutions can be accredited with star status like 5,4,3,2,1 star ) .Here the ordering is valid as 5 Star Rated institution is superior than 4 star rated institution.But the difference between the 5 and 4 star institutions and 4 and 3 institutions is not the same even though they differ by same number one.



c. Interval Scale Variables

When Variables measured on the interval measurement scales one unit on the scale represents the same magnitude on the characteristic being measured across the whole range of the scale. i.e. the interval between the numbers are equal. In the interval scale ratio between set of two numbers in the scale are not equal.
Temperature will be a perfect example for interval scales



d. Ratio Scale Variables

Ratio scale variables will have all the properties of interval variables and also the ratio between two numbers in the ratio scales is same.Theses scales will have a true zero.Weight and height.

Tutorial:3 Use of Biostatistical Tools in the planning stage of the research

After identifying and defining the problem clearly, researcher has decided about the type of study. Once the type of the study is decided he has to identify, classify variables before proceeding to the next step such as developing a hypothesis in case of experimental study. The variables can be classified according to their nature, type and scales of measurement i.e. independent or dependent, quantitative or qualitative, types such as nominal, ordinal, interval and ratio scales. Defining variables will have an effect on the collection and analysis part also.