Epidemiological studies of the non-specific effects of vaccines: II--methodological issues in the design and analysis of cohort studies.
We review sources of bias which can affect non-randomized cohort studies of non-specific effects of vaccines on child mortality. Using examples from the literature on non-specific effects, we describe different sources of selection and information bias, and, where possible, outline analysis strategies to mitigate or eliminate such biases.
Farrington
C P
CP
Department of Mathematics and Statistics, The Open University, Milton Keynes, UK. c.p.farrington@open.ac.uk
Firth
M J
MJ
Moulton
L H
LH
Ravn
H
H
Andersen
P K
PK
Evans
S
S
D015982:Bias; D002675:Child, Preschool; D015331:Cohort Studies; D005568:Forms and Records Control; D006801:Humans; D007223:Infant; D008499:Medical Records; D014611:Vaccination / Q000401:mortality*; D014612:Vaccines / Q000009:adverse effects
D014612:Vaccines