Microsoft Word research method fm doc

etc. 
Uses of descriptive studies 
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They can be done fairly quickly and easily. 
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Allow planners and administrators to allocate resources 
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Provide the first important clues about possible determinants of a disease (useful 
for the formulation of hypotheses) 
Types of descriptive studies 
 
a) Case reports and case series 
Case report:
a careful, detailed report by one or more clinicians of the profile of a single 
patient. 
 
The individual case report can be expanded to a case series, which describes characteristics 
of a number of patients with a given disease. 
Uses 
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Important link between clinical medicine and epidemiology
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One of the first steps in outbreak investigation
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Often useful for hypothesis generating and examining new diseases, but conclusions 
about etiology cannot be made. 
b) Ecological studies:
data from entire populations are used to compare disease 
frequencies between different groups during the same period of time 
or in the same population at different points in time. 

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Example:
Countries with low cigarette consumption have lower lung cancer rates than 
those countries with high cigarette consumption. 
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Ecological studies are usually quick and easy to do and can be done with already 
available information. 
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Since ecological studies refer to whole populations rather than to individuals, it is not 
possible to link an exposure to occurrence of disease in the same person. 
c) Cross-sectional studies 
 
A cross-sectional (prevalence) study provides information concerning the situation at a given 
time. In this type of study, the status of an individual with respect to the presence or absence 
of both exposure and disease is assessed at the same point in time. 
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Usually involve collection of new data. 
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In general, measure prevalence rather than incidence 
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Not good for studying rare diseases or diseases with short duration; also not ideal for 
studying rare exposures. 
 
For factors that remain unaltered over time, such as sex, blood group, etc., the cross-
sectional survey can provide evidence of a valid statistical association. 
As can be noted from the above explanation, a cross-sectional study can be either analytical 
or descriptive, according to its purpose. If data are collected both on exposures and 
outcomes of interest, and if the data are analysed so as to demonstrate differences either 
between exposed and non-exposed groups, with respect to the outcome, or between those 
with the outcome and those without the outcome, with respect to the exposure, then this is an 
analytical cross-sectional study. If the information collected is purely of a descriptive nature, 
not involving the comparison of groups formed on the basis of exposure or outcome status, 
then this is a descriptive cross-sectional study. Often a cross-sectional study may have both 
descriptive and analytical components. 
Nowadays, there is an increasing emphasis on the value of longitudinal studies in which 
observations are repeated in the same community over a prolonged period (i.e., longitudinal 

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studies provide the required data at more than one point in time unlike cross- sectional 
surveys).