Household Surveys: IFLS1 and IFLS2
Sample Design and Response Rates
The IFLS is a longitudinal survey, and so the sampling scheme for the first wave is the primary determinant of the sample in subsequent waves. The IFLS1 sampling scheme stratified on provinces, then randomly sampled within provinces. Provinces were selected to maximize representation of the population, capture the cultural and socioeconomic diversity of Indonesia, and be cost-effective to survey given the size and terrain of the country. The sample included 13 of Indonesias 26 provinces containing 83% of the population (see map).
Within each of the 13 provinces, enumeration areas (EAs) were randomly chosen from a nationally representative sample frame used in the 1993 SUSENAS, a socioeconomic survey of about 60,000 households. The IFLS randomly selected 321 enumeration areas in the 13 provinces, oversampling urban EAs and EAs in smaller provinces to facilitate urban-rural and Javanesenon-Javanese comparisons. Within a selected EA, field teams randomly selected households based upon 1993 SUSENAS listings obtained from regional BPS office.
For IFLS1 a total of 7,730 households were sampled to obtain a final sample size goal of 7,000 completed households. In fact, interviews were conducted with 7,224 households in IFLS1.
In IFLS2 our goal was to relocate and reinterview the 7,224 origin households interviewed in 1993. If no members of the household were found in the 1993 interview location, we asked local residents where the household had gone. If the household was thought to be within one of the 13 IFLS provinces, the household was tracked to the new location and if possible interviewed there. In IFLS2 a full 94% of IFLS1 households were relocated and reinterviewed. (That number includes the 69 IFLS1 households whose every 1993 member had died by 1997, according to local informants.)
In addition, we conducted interviews with 878 "split-off" households. These households resulted from tracking an IFLS1 household member who had left the "origin" household and interviewing them in their new location.
In IFLS1 it was determined to be too costly to interview all household members, so a sampling scheme was used to randomly select several members within a household to provide detailed individual information. IFLS1 conducted detailed interviews with the following household members:
- the household head and his/her spouse
- two randomly selected children of the head and spouse age 0 to 14
- an individual age 50 or older and his/her spouse, randomly selected from remaining members, and
- for a randomly selected 25% of the households, an individual age 15 to 49 and his/her spouse, randomly selected from remaining members.
In IFLS2 we attempted to interview all current members of the IFLS origin households.
In addition, there were two groups of people that we were committed to tracking if by 1997 they had moved out of the 1993 household. These two groups were:
- all IFLS1 household members who provided detailed individual-level data in 1993 (panel respondents)
- all IFLS1 household members who were born in 1968 or earlier
In IFLS1, the practice of sampling within the household yielded lower interview rates for certain groups, such as never-married adults and children born to someone other than the household head or spouse. In IFLS2 we attempted to interview all household members in origin households and a subset of members in split-off households. This protocol change yielded considerably higher interview rates in IFLS2 for a number of demographic subgroups. The tables below show, for IFLS1 and IFLS2 respectively, the number of interviews conducted with members of various demographic subgroups.
IFLS1 Samples, by Gender and Age
|Age Group||Both Males and Females||Males||Females|
|Children of head/spouse:|
|All older adults:|
Note: Excludes respondents whose age is unknown.
IFLS2 Samples, by Gender and Age
|Age Group||Both Males and Females||Males||Females|
|Children of head/spouse:|
|All older adults:|
The IFLS is a comprehensive multipurpose survey that asks both current and retrospective questions at the household and individual levels. The household questionnaire in IFLS2 was organized like its IFLS1 counterpart and repeated many of the same questions to allow comparisons across waves. The IFLS1 questionnaire contained many retrospective questions covering past events. In IFLS2, full retrospectives were asked of new respondents. For most sections, respondents interviewed in 1993 were only asked to update the information, starting approximately five years before the 1997 interview, so there is one year of overlap between IFLS1 and IFLS2 data.
The questionnaire was divided in books (usually addressed to different respondents) and subdivided into topical modules. Three books collected information at the household level, generally from the household head or spouse: book K, book 1, and book 2. The next four books collected individual-level data from adult respondents (books 3A and 3B), ever-married female respondents (book 4), and children younger than 15 (book 5). Individual measures of health status were recorded for each household member (book US). In IFLS2 household members between the ages of 7 and 24 were asked to participate in cognitive assessments of their skills in mathematics and Indonesian language (book EK).
The information provided below describes the IFLS2 questionnaires, which in most respects were very similar to the IFLS1 questionnaires. A more detailed description of the IFLS is provided in Volume 1 of the IFLS2 documentation. IFLS documentation is now available to the public.
Book K: Control Book and Household Roster. Book K recorded whether a household was found and interviewed and the location of the household. If the household was interviewed, information on the composition of the household was collected and on basic characteristics of the housing structure that the interviewer could observe. The interviewer filled out a portion of this book for all 7,224 households interviewed in the IFLS1, even if they were not interviewed in IFLS2. In addition, in IFLS2 book K was completed when individuals from origin households were tracked to a split-off household and interviewed there
Book 1: Expenditures and Knowledge of Health Facilities. This book was typically answered by a female respondent, either the spouse of the household head or another person most knowledgeable about household affairs. One module recorded information about household expenditures and about quantities and purchase prices of several staples. The other module probed the respondents knowledge of various types of public and private outpatient health care providers. This information was used in drawing the sample of facilities for interviews in the Community-Facility Survey. Book 1 was shortened in IFLS2 relative to IFLS1 to reduce the response burden on the household heads spouse, who typically received a very long interview.
Book 2: Household Economy. This book was typically answered by the household head or the heads spouse. Modules asked about household businesses (farm and nonfarm), nonbusiness assets, and nonlabor income. Combined with individual-level data on labor and nonlabor income collected in book 3, this information can be used to provide a complete picture of current household income resulting from market-wage income, self-employment income, family businesses, informal-sector activities, and unearned income. Other modules collected information about housing characteristics, economic shocks experienced by the household in the previous five years, and about the households plans to move in the future (helpful in planning for subsequent rounds of data collection).
Book 3A: Adult Information (part 1). This book asked all household members 15 years and older about their educational, marital, work, and migration histories. In addition, the book included questions on asset ownership and nonlabor income, household decision-making, fertility preferences, and (for women 50 and older) cumulative pregnancies.
The amount of retrospective information collected varied by module and by whether the respondent had answered book III in IFLS1. Nonrespondents to the earlier survey were typically asked for lengthy histories that mirrored the data obtained in IFLS1. Respondents who had answered book III in IFLS1 were generally asked only to update the information for the five years preceding the interview. The specific rules varied by module.
Book 3B: Adult Information (part 2). Book 3B emphasized current rather than retrospective information. Separate modules addressed insurance coverage, health conditions, use of inpatient and outpatient care, and participation in community development activities. Another module asked in detail about the existence and characteristics of non-coresident family members (parents, siblings, and children) and about whether money, goods, or services were transferred between these family members during the year before the interview.
Books 3A and 3B, one book in IFLS1, were separated in IFLS2 to establish a natural breaking place for the interview if respondents could not answer all the questions in one sitting.
Book 4: Ever-Married Woman Information. This book, administered to all ever-married women age 1549, collected retrospective life histories on marriage, children ever born, pregnancy outcomes and health-related behavior during pregnancy and childbirth, infant feeding practice, and contraceptive use. The marriage and pregnancy summary modules replicated those included in book 3 so that women who answered book 4 skipped these modules in book 3. Similarly, women who answered questions about non-coresident family in book 4 skipped that module in book 3. A separate module asked married women about their use of contraceptive methods on a monthly basis over the previous 5 to 10 years.
Book 5: Child Information. This book collected information about children younger than 15. For children younger than 11, the childs mother, female guardian, or caretaker answered the questions. Children between the ages of 11 and 14 were allowed to respond for themselves if they felt comfortable doing so. The five modules focused on the childs educational history, morbidities, self-treatment, and inpatient and outpatient visits. Each paralleled a module in the adult questionnaire (books 3A and B), with some age-appropriate modifications. For example, the list of acute health conditions specified conditions relevant to younger children.
Book US: Physical Health Assessments. In IFLS2 a nurse recorded various measures of physical health for each household member. The nurses received special training in taking the measurements, which included height and weight (all respondents), blood pressure and pulse (respondents 15 and older), lung capacity (respondents 9 and older), and hemoglobin (respondents 1 and older). In addition, respondents 15 and older were timed while they rose from a sitting to a standing position five times (a physical assessment developed by the WHO team). The nurse also evaluated the individuals health status on a 9-point scale and recorded comments about the individuals health. As an indication of household health, the iodine content of the households salt was tested. In IFLS1 measurements of height and weight were conducted.
Book EK: Cognitive assessments.In IFLS2 children between the ages of 7 and 24 were administered cognitive tests to assess their skills in the Indonesian language and in mathematics. The tests were designed by two members of the testing division of the Indonesian Ministry of Education, drawing items from the National Achievement Test (EBTANAS). Tests were originally designed to cover four levels (age 79, the first three years of elementary school; age 1012, the last three years of elementary school; age 1315, the three years of junior high school; and age 1624, senior high school and beyond). The first few weeks of fieldwork revealed that the highest test level was too difficult. Subsequently all respondents 1324 were given the same test, that originally designed for 1315-year-olds. These assessments were not administered in IFLS1.