POPWT Expansion Factor

For IPUMS-PMA samples that are nationally representative, IPUMS has created the variable POPWT to generate weighted count estimates of women aged 15 to 49 in each country. For example, POPWT could be used as an inflation factor to find the approximate number of women in Burkina Faso in 2014 who used implants as a family planning method.

The female weight constructed by PMA (FQWEIGHT), is a normalized weight. It will yield the correct proportion of the population with a characteristic, but it will not indicate the raw count of people that proportion represents. For example, using FQWEIGHT, a researcher can estimate the share of women of childbearing age in Burkina Faso who use implants for family planning. To convert such results into the total number of women using implants in that country, employ POPWT instead.

POPWT is designed to give estimates subject to the same margin of error as the original FQWEIGHT, in addition to the margin of error for population estimates provided by the United Nations Population Division. POPWT is representative at the same levels of geography as FQWEIGHT, as listed on our Sample Descriptions page.

Construction of POPWT:
  1. The total population of each country in each year of women aged 15 to 49 was collected from the United Nations Population Division and also found in Table 1.
  2. Calculate the sum of FQWEIGHT for all eligible women (age 15 to 49) within the sample of interest.
  3. POPWT of individual i = (FQWEIGHT of individual i / Sum of FQWEIGHT in the sample) * Total population of women 15 to 49 in that country in that year.

For example, using the Burkina Faso 2015 Round 2 sample in stata, a frequency tabulation of injectable users in Burkina Faso in 2015 shows that 6.37 percent of the sample reported currently using injectables.

			
tab fpnowusinj

current use of injectables |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
                        no |      2,013       93.63       93.63
                       yes |        137        6.37      100.00
---------------------------+-----------------------------------
			         Total |      2,150      100.00

When weighted with FQWEIGHT, the analysis estimates that 6.4 percent of women aged 15 to 49 in Burkina Faso used injectables as a family planning in that year.

			
tab fpnowusinj [iw=fqweight]

current use of injectables |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
                        no | 1,978.1077       93.60       93.60
                       yes | 135.306331        6.40      100.00
---------------------------+-----------------------------------
                     Total |  2,113.414      100.00

When weighted with POPWT instead of FQWEIGHT, the analysis estimates that approximately 257,194 women used injectables as a family planning method in Burkina Faso in 2015.

			
tab fpnowusinj [fw=popwt]

current use of injectables |      Freq.     Percent        Cum.
---------------------------+-----------------------------------
                        no |  3,760,024       93.60       93.60
                       yes |    257,194        6.40      100.00
---------------------------+-----------------------------------
                     Total |  4,017,218      100.00

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Table 1: Population figures used to construct POPWT
Populations of women 15 to 49 in PMA countries
Country 2013 2014 2015 2016 2017 2018 2019
Burkina Faso 4,048,311 4,177,966 4,310,176 4,447,000 4,588,000 4,736,000
Cote d'Ivoire 5,724,631 5,894,000
Ethiopia 23,293,011 24,150,141 24,991,034 25,857,217 26,737,000 27,622,000
Ghana 6,690,500 6,847,041 7,003,487 7,152,901 7,307,000
Indonesia 69,561,710 70,053,102
Kenya 11,500,737 11,871,474 12,256,380 12,638,000 13,019,000 13,652,000
Niger 4,328,124 4,498,230
Nigeria 42,479,202 43,671,554 44,930,000
Uganda 8,714,43 9,059,232 9,407,843 9,770,828 10,148,000 10,515,000