Microsoft Word research method fm doc

Practical questions such as the following could also arise
. 
- Is the proposed population the one that would give the required information? 
- Will the population cooperate to participate in the study, or will it be a 'resistant' one?
- If it is proposed to study patients with a specific disease, will it be possible to identify 
enough cases to yield useful conclusions? 
- If a long term 'follow up' study is planned, is the population so mobile that it may be 
difficult to maintain contact with the subjects? 
A preliminary exploratory study may sometimes be required in order to answer such 
questions.
 
6.5 Operational Definitions of Variables 
Before we directly go to the operational definition of variables it would be important to discuss 
about the nature of variables first. 
Definition
: A variable is a characteristic of a person, object, or phenomenon that can take on 
different values. 

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Research methodology 
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A simple example of a variable is a person's age. The variable can take on different values, 
such as, 20 years old, 30 years old, and so on. Other examples of variables are: 
a) weight in kilograms 
b) height in centimeters 
c) monthly income in Birr 
d) marital status (single, married, divorced and widowed) 
e) job satisfaction index (1 to 5) 
f) occupation (civil servant, farmer, student, et.) 
g) disease condition (presence or absence of a disease) 
The first three variables (a to c) are numerical variables because they are expressed in 
numbers (metric data). Since the values of the remaining three variables (d to g) are 
expressed in categories, we call them categorical variables. 
Because in the health research we often look for associations, it is important to make a 
distinction between dependent and independent variables. Both the dependent and 
independent variables together with their operational definitions (when necessary) should be 
stated. 
Definitions: 
The variable that is used to describe or measure the problem under study is called the 
dependent variable. The variables that are used to describe or measure the factors that are 
assumed to influence (or cause) the problem are called independent variables. 
For example, in a study of relationship between smoking and lung cancer, "suffering from 
lung cancer" (with the values yes, no) would be the dependent variable and "smoking" (with 
the values no, less than a packet/day, 1 to 2 packets/day, more than 2 packets/day) would be 
the independent variable.