Unit 4
Sources of Data Used in
Epidemiology
Unit 4: Learning Objectives
• Identify bibliographic databases for locating
epidemiological literature
• Identify US government sources of
epidemiological data census, vital statistics
• Understand criteria for quality and utility of
epidemiological data
• Discuss strengths and weakness of various data
sources
This is one of those topics that will assist with
your journal critique exercise..
Garbage in Garbage out
• Research findings are only as good as the data
upon which they are based
• Findings from bad data leads to bad decision
making..
Source of Data
Statistics derived from vital
registration systems
Disease statistics
Notifiable disease statistics
Morbidity surveys of the
general population
Clinic based surveys
Screening surveys
Disease registries
Insurance data
Hospital data
Physician Practice data
Description
Aggregate in nature
Aggregate in nature
Aggregate in nature
Person level
Person-level
Person-level
Person-level
Person-level
Person-level
Person-level
Personal-level data sources
• The personal level data sources in the previous
slide can be used to design various study designs
• Cross-sectional studies
• Retrospective cohort studies
• Case controls studies
• When conducting your journal critique one of the
things you can assess strengths and weaknesses in
is the data source of your stud
Criteria for Quality and Utility of
Epidemiological Data
• For practical purposes, the pressing issue
when judging quality and utility of data
sources is to consider which source of data
helps you answer the research question
posed with the greatest possible accuracy
Exposure
Outcome
Criteria for Quality and Utility of
Epidemiological Data
1. Nature of the Data
 Bottom line is where the records originate can
help one
judge the accuracy of their collection
Criteria for Quality and Utility of
Epidemiological Data
2. Availability of data
 Bottom line is some useful data may not be
available or available consistently or completely
example, zipcode, bmi, race , income
Criteria for Quality and Utility of
Epidemiological Data
3. Population coverage
(representativeness/external
validity
 The bottom line is some data may not be an
adequate representation of your target
population.ie omission of minorities, low SES
Criteria for Quality and Utility of
Epidemiological Data
4. Population coverage
(thoroughness)
 The bottom line is some data may not include all
possible cases. Example hospital data may only
contain severe cases.
Criteria for Quality and Utility of
Epidemiological Data
5. Strengths vs. Limitations
 Bottom line is that considering certain strengths
and limitations inherent in data sources helps to
judge quality and utility
 Duplicate cases, incomplete case info are issues for
some data sets and not others
You should panic if you…
• Do not know weaknesses and strengths of
using different personal-level-data sources
to be able to critique study designs using
them
• Do not know the criteria for judging the
quality of data sources to critique study
designs using them
Text book reference showing
strengths and weaknesses of
epidemiological data sources
table 5-1 page 213