Descriptive studies

1. Dr.A.P. Kulkarni
Professor & Head
Department of Community Medicine
Rural Medical College, LONI
DESCRIPTIVE STUDY

2. Lesson Objectives
At the end of the lesson, the participants will be
able to:
1.Enlist the characteristics of Descriptive study
2.Enlist indications of Descriptive study
3.Describe the steps in cross sectional study
4.Describe common issues related to cross sectional
study

3. Common study designs

4. DescriptiveStudy: Characteristics
Observational type of quantitative study
RQ descriptive type
No hypothesis
No comparison group
Sub-groups in observed group may be
compared
Can be conducted in hospital /
community

5. DescriptiveStudy: Characteristics
Objectives
1.To describe disease / health related event
(Person, place, time??): thereby generate hypothesis
2.To estimate prevalence/ incidence
3.To estimate mean

6. DESCRIPIVE STUDY: Indications
RQ is descriptive
Describing disease/ health
related phenomena
Quantification of disease/
health related problem
Generation of hypothesis
Types
1. Case report/ series
2. Cross sectional
3. Longitudinal
Cross sectional study
 Measurement of variable
in RQ only once
 Like one snap shot
Longitudinal study
 Measurement of variable
in RQ more than once
 Series of Cross sectional
studies for one RQ
 Series of snap shots

7. CROSSSECTIONAL STUDY: Steps
1. Set RQ, Enlist variables
2. Decide tools / methods of measurement of each
variable
3. Define population
4. Estimating sample size and deciding sampling method
5. Collection of data
6. Editing data
7. Analyze data
8. Hypothesis formulation
9. Write report
Two examples
1.What is the prevalence of
hypertension in residents
of LONI aged 40+ ?
2.What is the profile of
anemia in ANCs attending
RMC Loni?

8. DESCRIPIVE STUDY: Steps
1. Set RQ & Define
variables
 Must be descriptive
type
 Enlist variables in RQ
and other variables like
age, gender,
occupation etc
2. Decide tools of
measuring each
variable
Example:
Hypertension:
Examination
Age: By interview
Gender: By interview

9. DESCRIPIVE STUDY: Steps
Variable Method of
measurement
Statistical
scale
Hypertensio
n
Examination Ratio
Age Interview Ratio
Gender Interview Nominal
SE status Interview Ordinal
2. Decide
tools of
measuring
each
variable

10. DESCRIPIVE STUDY: Steps
3. Define population
 Inclusion criteria
 Exclusion criteria
 Enlisting eligible
population/
participants
Inclusion: Resident of Loni
for past 6 months or
more
Exclusion:
Probable
participants
Inclusion
criteria
Exclusion
criteria

11. DESCRIPIVE STUDY: Steps
4. Sample size
determination &
Sampling method
 Consult statistician /
epidemiologist
 Sample size
- Alpha error
- Precision
- Frequency of variable
in RQ
 Sampling method
Depends on type of
population
Eligible
population
Sample

12. DESCRIPIVE STUDY: Steps
5. Collection of data
 Use pre-decided
tools / methods
 Administrative/
operational planning
 Durable recording
 Use of computers
6. Editing data
 Check for
- Completeness
-“illegal entries”
-Check for out-liers
-“Improbable
entries”
 Use of soft ware

13. DESCRIPIVE STUDY: Steps
7. Analysis of data
 Grouping and tables
 Descriptive
statistics: Mean,
Range, SD,
Proportions
 Graphs
8. Hypothesis
formulation
Techniques
 Method of similarity &
difference
 Method of concomitant
variation
 Method of analogy
Use of statistical tests

14. DESCRIPIVE STUDY: Steps
9. Report writing
 For whom? :
Journal,
Sponsorer, HOI
 Format
Issues in descriptive studies
 Validity: External; Internal
 Bias
 Sample size
Longitudinal study
 Series of cross sectional
studies for same RQ in same
population
 For Incidence / Time related
question

15. CROSSSECTIONAL STUDY:
Summary
1. The characteristics of Descriptive study
2. Indications of Descriptive study
3. Steps in cross sectional study
4. Common issues related to cross sectional study

16. 16
Thank You !

17. Dr.A.P. Kulkarni
Professor & Head
Department of Community Medicine
Rural Medical College, LONI
LONGITUDINAL STUDY

18. Longitudinal Study: Characteristics
Observational type of quantitative study
RQ descriptive type
No hypothesis
No comparison group
Sub-groups in observed group may be compared
Can be conducted in hospital / community
When time characteristics are to be studied

19. Longitudinal Study: Characteristics
Objectives
1.To describe disease / health related event (Person, place,
time): thereby generate hypothesis
2.To estimate prevalence/ incidence
3.To estimate mean
Longitudinal study is nothing but Cross
sectional study repeated over period of time

20. Longitudinal Study: Characteristics
Examples
Seasonal variation in incidence of malaria
Incidence ofTB
Diurnal variation of temperature in febrile illness

21. Longitudinal Study: Characteristics
Same population, Same
sample over period of time
Same population, different
samples each time

22. Longitudinal Study: Spl. problems
1. Periodicity:Weekly, Fortnightly, Monthly,
Quarterly, Season
2. Uniformity of measurement tools
3. Loss to follow-up
4. Maintaining interest
5. Cost & resources
6. Sampling