F2. DESCRIPTIVE studies: Ecologic study.

Question 1

• amount or occurrence
• distribution
• identifying non-random variation
• 1st step in risk factor determination
• data lead to formulation of research hypothesis

Answer 1

Descriptive study.

Question 2

they are routinely collected.

Answer 2

Descriptive study

examples: census, vital registries, clinical records, employment
health examination

Question 3

3 uses of descriptive statistics:

Answer 3

1. trend analysis.
2. health care planning.
3. hypothesis generation.

Question 4

describe patterns of disease occurrenc

Answer 4

trend analysis.

Question 5

• efficient allocation of resources
• health promotion and prevention programs for identified groups

Answer 5

health care planning.

Question 6

• formulation of research questions & hypothesis
• 1st step in risk factor determination

Answer 6

hypothesis generation.

Question 7

Types of descriptive studies?

Answer 7

1. ecologic [correlational studies].
2. case report/ case series.
3. cross-sectional studies [prevalence studies].

Question 8

ecologic studies is also known as?

Answer 8

correlational/ aggregate studies.

Question 9

• measures the characteristics entire population
• comparison of groups
• describes disease in relation to a factor of interest

Answer 9

ecologic studies.

Question 10

important CHARACTERISTICS of ECOLOGIC STUDIES:

Answer 10

1. group.
2. average exposure and disease levels.
3. secondary sources of data.
4. prevalence, incidence, or mortality data.

Question 11

types of Ecologic studies:

Answer 11

1. multi-group design.
2. time-trend design.
3. mixed design.

Question 12

• search for SPATIAL PATTERN.
• compare rate of diseases among DIFFERENT regions during SAME PERIOD.

Answer 12

multi-group design.

Question 13

compare rate of disease OVER TIME in GEOGRAPHICALLY DEFINED population

one region only.

it is also known as?

Answer 13

time-trend design.

ecologic trend.

Question 14

combination of multi-group & time-trend design.

Answer 14

mixed design.

Question 15

advantages of ecologic studies:

Answer 15

1. low cost & convenience.
2. overcome MEASUREMENT & DESIGN limitations of individual level studies.
3. ecological effects
4. simplicity of analysis and presentation

Question 16

disadvantages of ecologic studies:

Answer 16

1. cannot link E w/ D at individual level.
2. only AVERAGE exposure and disease levels.
3. lack of ability to control for effects of potential confounding factors.

Question 17

1. graphical presentation of ecologic study?
2. computations of ecologic study?
3. linear regression analysis of ecologic study?

Answer 17

1. scatter-plot.
2. correlational coefficient (r) & coefficient of determination.
3. Y = a + bX.