surveys and cross sectional studies

Question 1

what is a survey

Answer 1

instrument for measuring something in a population - asking questions or taking measurements from sample in that population

Question 2

cross sectional

Answer 2

take information from 1 point in time
prevalence studies - existing cases
descriptive or analytical if investigate association
distribution of factors can be describes in relation to time person place

Question 3

use of x sectional stidies

Answer 3

prevalence
association between risk factor and disease
experience of patients
explore knowledge attitudes and beliefs of patients - relate to treatment regimes
may also look at continuous exposure and outcome - but these are followed up by complex analysis to avoid confounding

Question 4

data collection

Answer 4

depend on the exposure or outcome being measured
questionairres
clinical examination 
investigation 
routine sources

Question 5

analysis and interpretation

Answer 5

calculate prevalence
period prevalence includes new and old
association between exposure and disease - prevalence ratio
odds ratio

Question 6

prevalence ratio =

Answer 6

prevalence in exposed/prevalence in unexposed

Question 7

look at results

Answer 7

clear definitions of cases and controls
reasonable response rate
validated/ pioleted and tested questions - avoid measurement bias
validity of routine sources
known confounders measured and adjusted for
reverse causality

Question 8

strengths

Answer 8

easy and quick
cheap
wide range of exposures and outcomes at the same time
regular surveys provide valuable snapshots

Question 9

limitations

Answer 9

biased towards chronic illness rather than acute - only prevalent cases included
difficult to assess temporal relationship

Question 10

test to determine significance of associations

Answer 10

chi squared