F2. ANALYTICAL studies: Cross-sectional studies.

Question 1

• to test a hypothesis
• a statement about the relationship between 2 variables
• the use of a comparison group

Answer 1

analytic studies.

Question 2

types of analytical studies:
1. w/o manipulation.
2. w/ manipulation.

Answer 2

1. observational.
2. experimental.

Question 3

1. E and O/D is measure at present time, one point in time, or over a very short period of time.
2. use to estimate prevalence

Answer 3

1. cross-sectional studies.
2. prevalence study/ survey.

Question 4

use of cross-sectional studies:

Answer 4

1. snapshots frequency & characteristics of disease.
2. infos about prevalence of disease.
3. monitor changes.
4. make inference about risk.
5. association between coexisting variables.

Question 5

cross-sectional studies steps:

Answer 5

1. Choose study population
2. Draw an adequate # of subjects by scientific sampling techniques
3. Collect data
4. Analyze data

Question 6

cross-sectional methods of analysis:

Answer 6

1. measures of disease occurence.
2. measures of **association. **

Question 7

• prevalence proportion
• disease/ prevalence odds

Answer 7

Measures of disease occurrence

Question 8

• prevalence difference
• prevalence ratio
• odds ratio

Answer 8

Measures of association

Question 9

prevalence ratio interpretation:
1. 1.0/ null value.
2. > 1.
3. < 1.

Answer 9

1. no association.
2. positive association/ direct.
3. negative association/ indirect.

Question 10

advantages of cross-sectional studies.

Answer 10

• resource-efficient
• does not suffer from lost to follow-up
• generizable

Question 11

limitation of cross-sectional studies.

Answer 11

1. no temporal relationship.
2. unable to establish causality.
3. lacks info about past E.
4. may miss disease of short duration or with periods of remission
5. suffer from selection bias: response & survival bias.