Research methodology
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Pretesting
is: 1
. Simpler
2
. Less time consuming
3. Less costly than conducting an entire pilot study.
Therefore, pretesting is recommended as an essential step in the development of the
research projects.
It is useful in examining the practicability,
reliability and
suitability of the
method.
The comments of the respondents will help in
improving the sequence and
layout of the
questionnaire. It is also important to know the
time taken by the interview.
In
a community study, cooperation can be enhanced by suitable
public relations and
preparatory educational work
in the community. The
best results are provided by contacts
with key individuals
and
organizations in the community.
6.13 Exercises
1. Identify the most appropriate study design for the research proposal you are
planning to develop.
2. Describe the various data collection techniques and state their uses and limitations.
3. State the differences between quantitative and qualitative
research methods by
giving appropriate examples.
4. A nutritionist wants to determine the prevalence of malnutrition among under 5
children in Amhara region. If a sample of 3000 children is required, what is the
sampling technique he should use to select the required subjects. Write a short note
on the procedures (steps) he should follow in selecting these subjects.
5. In a school there are about 1800 students and the investigator
wants to determine
the prevalence of a certain character (eg., KAP on HIV/AIDS) by taking 450
students. The following table gives the distribution of students by grade and number
of sections.
Research methodology
84
Grade Number of
students
Number of
sections
9
10
11
12
600
500
400
300
8
7
6
5
Total
1800
26
a) What type of sampling technique do you use? Why?
b) How do you select the subjects who will be included in your sample?
6. A multi-national clinical trial is proposed to investigate
the value of a gradually
increasing dose schedule of a beta blocker in the treatment of severe heart failure.
The trial will be randomised, double-blind and placebo controlled. Each patient is to
be followed for 2 years, and the main treatment comparison is for all cause
mortality. Previous experience suggests a 2 year mortality rate of around 30%. The
investigators propose that a one-third reduction in mortality
due to beta-blockade
would be important to detect. They suggest that type I and type II errors be set at
.05 and .1, respectively.
a) Calculate the required number of patients to be recruited.
b) Suppose one anticipates that 10% of patients randomised to beta-blockade will fail
to comply with the intended treatment policy. What change in required sample
size would you suggest?
7. Prepare
your data-collection tools, taking care that you cover all important variables
of your proposed study.