"The first round of the panel, the Egypt Labor Market Survey of 1998 (ELMS 1998) was carried out on a nationally representative sample of 4,816 households containing 23,997 individuals. The original sample of the ELMS 1998 was selected from 200 primary sampling units (PSUs) across Egypt. The 1998 sample was a two-stage stratified random sample selected from a master sample prepared by CAPMAS and over-sampled urban areas. In 1998, the PSUs were selected according to the probability proportional to size (PPS) method.
The ELMPS 2006 followed the initial ELMS 1998 sample, locating 3,685 households from the original ELMS 1998 survey and adding 2,168 new households that emerged from these households as a result of splits, as well as a refresher sample of 2,498 households, all totaling 8,351 households containing 37,140 individuals.
In 2006, the refresher sample of households was selected from an additional 100 PSUs randomly selected from a new master sample prepared by CAPMAS. The ELMPS 2012 is therefore the third round of a periodic longitudinal survey that tracks the labor market and the demographic characteristics of households and individuals interviewed in 2006, both individuals included in the ELMS 1998 and individuals added in 2006, as well as a refresher sample of 2,000 new households to ensure that the data continues to be nationally representative, a total sample of 12,060 households and 49,186 individuals.
The field work for the ELMPS 2012 was carried out from March to June of 2012. In 2012, the refresher sample of 2,000 households was selected from an additional 200 PSUs randomly selected from a new master sample prepared by CAPMAS. By design, the 2012 refresher sample over-sampled areas with high migration rates.
The attrition that occurred from the original 1998 sample to 2006 was mostly random in nature, due to the loss of records containing identifying information for 1998 households (Assaad and Roushdy 2009). The attrition that occurred from the 2006 sample to the 2012 sample was due to a variety of processes. [...]
The final sample for the ELMPS 2012 was 12,060 households, consisting of 6,752 households from the 2006 sample, 3,308 new households that emerged from these households as a result of splits, and a refresher sample of 2,000 households. Of the 37,140 individuals interviewed in the 2006 survey, 28,770 (77 percent) were successfully re-interviewed in 2012. These individuals, 13,218 of whom were also tracked in 1998, form a panel that can be used for longitudinal analysis. The 2012 sample also includes 20,416 new individuals." (Assaad and Krafft, 2013)
For details on The Pattern of Attrition from 2006 to 2012, see:
Assaad, R., and Krafft, C. (2013). The Egypt Labor Market Panel Survey: Introducing the 2012 Round. Economic Research Forum Working Paper No. 758