Data Appraisal
SAMPLE SIZE
One hundred and twenty (120) EAs were selected in 12 replicates in each State from the NISH master sample frame in replicates (4-15). However, 60 EAs were selected in the Federal Capital Territory. Five (5) housing units (HUs) were scientifically selected in each of the selected EAs. One replicate consisting of 10 EAs in the State and 5 EAs in the Federal Capital Territory were covered every month. Fifty (50) HUs were covered in each State and 25 HUs in the Federal Capital Territory per month. This implied that the survey had an anticipated national sample size of twenty-one thousand and nine hundred (21,900) HUs for the country for the 12-month survey period. Each State had a sample size of 600 HUs, while the Federal Capital Territory had a sample size of 300. The sample size is robust enough to provide reasonable estimates at national and sub-national (State) levels.
ESTIMATION PROCEDURE
The following statistical notations were used:
N = the number of EAs in each State
ni = Size of replicates rth
r = number of replicates in a State
H = number of housing units listed in the ith selected EA.
Xhj = number of housing units selected from ith selected EA.
Wrij = weight of the replicate =
Yrij = total value of variable from the ith HU of ith selected EA.
Replicate Estimate (Monthly Estimate)
Annual State Estimate
Sampling Error (Variance) Estimate
The Jacknife indefinite method of variance estimation was used for the survey because the method required replication and clustering.
An estimate of State variance was first obtained.
Cluster estimate is 
Mean Estimate
Therefore mean variance is
where 
