This research has been done to show the point estimate of the population total of Nigeria based on 2006
census resultand to examine the effect of the use of auxiliary information in estimating variance in collapsing of
strata with one unit per stratum. Two stage sampling method was used for the sample selection, which involves
two phases of selection. In the first stage, 12 states were selected out of 36 states using random number table.
The Local Government Areas (774) were taken to be the second stage and purposive sampling method was
used. Based on the research work, considering one unit per stratum, that is selecting one Local Government
Area was selected from each of the selected state. Based on the result obtained, using stratified random sampling
with addition of auxiliary variable, the least standard error of
Ystr
ˆ
was 3,501,901.105under the collapsing of
12 strata in six into two groups with an estimated population total of 139,295,482 which was very close to the
actual population total of Nigeria based on 2006 census result(140,003,542).
Estimation using stratified sampling with addition of an auxiliary variable gave a better result than estimation
with variable of interest only