Methodology
Survey design, sampling methodology, and statistical analysis approaches
Survey Design
Children's Dental Health Survey 2013
The 2013 CDHS used a multi-stage stratified cluster sampling design:
- Stage 1: Primary Sampling Units (PSUs) - regions and local authorities selected with probability proportional to size
- Stage 2: School groups selected randomly without replacement
- Stage 3: Schools within groups by simple random sampling
- Stage 4: Children within schools by sequential random sampling
Adult Dental Health Survey 2009
The 2009 ADHS employed a stratified two-stage cluster sampling design with postcode sectors as primary sampling units and addresses as secondary units.
Survey Weights
Survey weights adjust for unequal selection probabilities and non-response. Different weights are provided for different types of analysis:
| Weight Variable | Use For |
|---|---|
| eweight | Clinical examination variables (e.g., DMFT, decay counts) |
| ppweight | Pupil self-completion questionnaire variables |
| prweight | Parent/guardian questionnaire variables |
Statistical Methods
Survey-Weighted Analysis
All analyses in XeraCDHS use survey-weighted methods that account for:
- Complex sampling design (stratification and clustering)
- Unequal selection probabilities
- Non-response adjustments
Available Regression Models
Linear Regression
Continuous outcomes
svyglm(y ~ x, design, family = gaussian())Logistic Regression
Binary outcomes (0/1)
svyglm(y ~ x, design, family = quasibinomial())Poisson Regression
Count outcomes
svyglm(y ~ x, design, family = poisson())Negative Binomial
Overdispersed count outcomes
svyglm(y ~ x, design, family = quasipoisson())