The survey involves the collection of data on demographic and socio-economic characteristics of working children with ages 5 to 17 through personal interviews.

The survey adopts the sampling design of the regular quarterly Integrated Survey of Households which is a stratified two-stage design with the barangays as the primary sampling units (PSU) and the households as the secondary sampling unit (SSU).

The urban and rural areas of each province are the principal domains of the survey. In addition, the urban and rural areas of cities and municipalities with a population of 150,000 or more as of 1990 are also made domains of the survey. These cities are the four cities in Metro Manila (Manila, Quezon City, Pasay, and Caloocan) and the cities of Angeles, Olongapo, Iloilo, Cebu, Zamboanga, Butuan, Cagayan de Oro, Davao and Iligan. With the creation of the Autonomous Region of Muslim Mindanao (ARMM), Marawi City and Cotabato City are also made domains of the survey.

The rest of Metro Manila, i.e., Pasig, Makati, and the 11 other municipalities, are treated as three separate domains. In the case of Makati, six exclusive villages are identified and samples are selected using a different scheme. These villages are Forbes Park, Bel-Air, Dasmarinas, San Lorenzo, Urdaneta and Magallanes.

In general, the sample design results in self-weighting samples with a uniform sampling fraction of 1:400 for urban and 1:600 for rural areas. However, special areas are assigned different sampling fractions so as to obtain "adequate" samples for each. Special areas refer to the urban and rural areas of a province or large city which are small relative to their counterparts. These special areas and their sampling rates are as discussed on next page:

(households as units)

Urban
Batanes 1:30
Mt. Province 1:90
Ifugao 1:90
Siquijor 1:60
Iligan City 1:360
Camiguin 1:150
Quirino 1:120
Kalinga Apayao 1:210
Abra 1:240
Aurora 1:330
Basilan 1:270
Tawi-Tawi 1:300
Marinduque 1:120
Romblon 1:240
Catanduanes 1:180
Southern Leyte 1:360
Butuan City 1:300

Rural
Batanes 1:60
Camiguin 1:240
Cabanatuan City 1:90
Cagayan de Oro City 1:120
Batangas City 1:300
Lipa City 1:300
San Pablo City 1:480
Aurora 1:570

For the purpose of selecting the PSUs, the barangays in each domain are arranged by population size (as of the 1990 Census of Population) in descending order and then grouped into strata of approximately equal sizes. Four independent PSUs are drawn with probability proportional to size.

Within each PSU selected at the first stage, a predetermined number of households (i.e. SSUs) is selected at the second stage using a systematic selection procedure with a random start. The number of households chosen from the i^th PSU is obtained from equation (1) below, which takes into account the probability of selecting the PSUs at the first stage such that each household within the domain has the same overall probability of selection for the survey (i.e. the sample is self-weighting within domains).
 
 

1 P_h⁹⁰ N_hi

n_hi = ---- * -------- * ----- (1)
b_h P_hi⁹⁰ R_k

where:

R_k = raising factor for the k_th domain (urban/rural area of province, city, or special area)

N_hi = number of households listed in the i^th PSU of the h^th stratum

b_h = the number of sample barangays drawn to represent the h_th stratum

P_h⁹⁰ = the 1990 population of all barangays in the h_th stratum

P_hi⁹⁰ = the 1990 population of the i_th sample barangay in the h_th stratum

k = 1 for urban, 2 for rural
 
 

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Two questionnaires were used for the survey. All LFS sample households identified to have children 5 - 17 years old are taken as samples/respondents for the Socio-Economic Profile of Filipino Households (SCL Form 1). From these selected sample households, all children identified to have worked at any time even for only one hour for the past 12 months were taken as respondents for the Survey on Children 5 -17 years old (SCL Form 2).

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There are two types of non-response encountered for this survey: interview non-response and item non-response. Interview non-response are those cases in which a sample household or a sample child could not be interviewed due to refusals or unavailability during the enumeration. To account for these cases, adjustment factors are introduced in the estimation of survey results. These factors are the following:

n_k/n_k’ = adjustment for LFS sample non-response in the k_th domain

n_k’’/n_k’’’ = adjustment for SCL 1 sample non-response in the k_th domain

c_k/c_k ‘ = adjustment for SCL 2 sample non-response in the k_th domain

where:

n_k = expected number of LFS sample households for all barangays in the k_th domain

n_k’ = actual number of LFS sample households for all barangays in the k_th domain

n_k’’ = the expected number of SCL 1 sample households (i.e. households with children 5 - 17 years old ) out of the responding LFS sample households for all barangays in the k_th domain

n_k’’’ = actual number of SCL 1 sample households for all barangays in the k_th domain

c_k = expected number of working children 5 - 17 years old from the responding SCL 1 sample households for all barangays in the k_th domain

c_k ‘ = actual number of working children 5 - 17 years old for all barangays in the k_th domain

Item non-response or the failure to obtain responses to particular survey items, results from such factors as respondents being unaware of the answer to a particular question and/or being unwilling to provide the requested information. Such cases are reported as Not-Reported in the tabulation.

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The independent estimate for the k_th domain total are given by the equations,

SCL 1

n_k n_k’’ H_k b_h d_i

x’_k = R_k * ------ * ---- * S S S x_hij (2)

n_k’ n_k’’’ _{h=1 i=1 j = 1}

SCL 2
 
 

n_k n_k’’ c_k H_k b_h d_i m_j

x’_k = R_k * ------ * ---- * ----- * S S S S x_hijl (3)

n_k’ n_k’’’ c_k ‘ _{h=1 i =1 j=1 l=1}

where

x_hij = value of the characteristic for the j_th household of the i_th sample PSU in the h_th stratum

x_hijl = value of the characteristics for the l_th child of the j_th household in the i_th sample PSU in the h_th stratum

x’_k = estimated total of the value of the characteristic for the k_th domain

H_k = number of strata in the k_th domain of the province

d_i = number of sample households in the i_th stratum

m_j = number of working children 5 - 17 years old in the j_th household

These estimates however, need to be adjusted to an independent population estimate for the province as follows:

SCL 1

P^c³ ₁₅ 2

_k = ------- * S x’_k (4)

P’³ _{15 k =1}

P^c< ₁₅ 2 P^c&sup3; ₁₅ 2

_k = ------- * S x’_k < 15 + ------- * S x’_k &sup3; 15 (5)

P’< _{15 k =1} P’&sup3; _{15 k =1}

where,

_k < 15 = estimated total of the value of the characteristic for children less than 15 years old in the k_th domain

_k &sup3; 15 = estimated total of the value of the characteristic for children 15 years old and over in the k_th domain

P^c ₁₅ = projected population of children less than 15 years old for the province

P^c&sup3; ₁₅ = projected population of children aged 15 years and over for the province

P’< ₁₅ = survey estimate of the number of children less than 15 years old for the province

P’&sup3; ₁₅ = survey estimate of the number of children 15 years and over for the province

Estimates for SCL2 are computed in the same manner as SCL1 using the respective variables. Provincial, regional and national totals are derived by aggregating the relevant age group, domain and provincial estimates.

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Survey Questionnaires and Variable Description

SCL Form 1. Survey on Socio-Economic Profile of Filipino Households

SCL Form 2. Survey of Children 5 - 17 Years Old

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