This appendix outlines various technical issues relating to the Post-enumeration Survey estimation.
1. Dwelling Weights
A dwelling weight is assigned to each dwelling in the PES simply to reflect the probability of that dwelling being selected:
Dwelling Weight = Si × Wh
Si = selection probability for the dwelling in PSU i
Wh = ratio weight representing the probability of a PSU being selected in stratum h
2. Person Weights
A person weight is assigned to each responding individual in the PES. The final weight reflects the probability of the person being included in the PES, and an adjustment for non-response:
Person Weight = Si × Wh × RESFACTr
Si = selection probability for the dwelling in PSU i
Wh = ratio weight representing the probability of a PSU being selected in stratum h
RESFACTr = non-response adjustment factor in region r
3. Non-response Adjustment
Data collected from responding dwellings is rated up to reflect the level of non-response amongst dwellings in the same region. Effectively, non-responding dwellings are imputed from the weighted average values of x and y from all responding dwellings in the same region. Response factors by region are calculated as follows:
| RESFACTr = |
Estimated number of dwellings in region r |
|
Sum of weights (Si × Wh) for responding PES dwellings in region r |
Regions used for non-response adjustment are Northland, Auckland, Waikato, Bay of Plenty, Gisborne/Hawke’s Bay, Taranaki, Manawatu-Wanganui, Wellington, Tasman/Nelson/Marlborough/West Coast, Canterbury, Otago and Southland.