Demographic and Health Survey (standard) - DHS III
The 1998 Philippines Demographic and Health Survey (PDHS) is the seventh DHS survey carried out every five years since 1968 in order to measure trends in demographic and family planning indicators in Philippines. But the 1998 NDHS is the second national sample survey undertaken in Philippines under the auspices of the worldwide Demographic and Health Surveys program.
The 1998 Philippines National Demographic and Health Survey (NDHS). is a nationally-representative survey of 13,983 women age 15-49. The NDHS was designed to provide information on levels and trends of fertility, family planning knowledge and use, infant and child mortality, and maternal and child health. It was implemented by the National Statistics Office in collaboration with the Department of Health (DOH). Macro International Inc. of Calverton, Maryland provided technical assistance to the project, while financial assistance was provided by the U.S. Agency for International Development (USAID) and the DOH. Fieldwork for the NDHS took place from early March to early May 1998.
The primary objective of the NDHS is to Provide up-to-date information on fertility levels; determinants of fertility; fertility preferences; infant and childhood mortality levels; awareness, approval, and use of family planning methods; breastfeeding practices; and maternal and child health. This information is intended to assist policy makers and program managers in evaluating and designing programs and strategies for improving health and family planning services in the country.
Survey data generally confirm patterns observed in the 1993 National Demographic Survey (NDS), showing increasing contraceptive use and declining fertility.
Fertility Decline. The NDHS data indicate that fertility continues to decline gradually but steadily. At current levels, women will give birth an average of 3.7 children per woman during their reproductive years, a decline from the level of 4.1 recorded in the 1993 NDS. A total fertility rate of 3.7, however, is still considerably higher than the rates prevailing in neighboring Southeast Asian countries.
Fertility Differentials. Survey data show that the large differential between urban and rural fertility levels is widening even further. While the total fertility rate in urban areas declined by about 15 percent over the last five years (from 3.5 to 3.0), the rate among rural women barely declined at all (from 4.8 to 4.7). Consequently, rural women give birth to almost two children more than urban women.
Significant differences in fertility levels by region still exist. For example, fertility is more than twice as high in Eastern Visayas and Bicol Regions (with total fertility rates well over 5 births per woman) than in Metro Manila (with a rate of 2.5 births per woman).
Fertility levels are closely related to women's education. Women with no formal education give birth to an average of 5.0 children in their lifetime, compared to 2.9 for women with at least some college education. Women with either elementary or high school education have intermediate fertility rates.
Family Size Norms. One reason that fertility has not fallen more rapidly is that women in the Philippines still want moderately large families. Only one-third of women say they would ideally like to have one or two children, while another third state a desire for three children. The remaining third say they would choose four or more children. Overall, the mean ideal family size among all women is 3.2 children, identical to the mean found in 1993.
Unplanned Fertility. Another reason for the relatively high fertility level is that unplanned pregnancies are still common in the Philippines. Overall, 45 percent of births in the five years prior to the survey were reported to be unplanned; 27 percent were mistimed (wanted later) and 18 percent were unwanted. If unwanted births could be eliminated altogether, the total fertility rate in the Philippines would be 2.7 births per woman instead of the actual level of 3.7.
Age at First Birth. Fertility rates would be even higher if Filipino women did not have a pattem of late childbearing. The median age at first birth is 23 years in the Philippines, considerably higher than in most other countries. Another factor that holds down the overall level of fertility is the fact that about 9 or 10 percent of women never give birth, higher than the level of 3-4 percent found in most developing countries.
Increasing Use of Contraception. A major cause of declining fertility in the Philippines has been the gradual but fairly steady increase in contraceptive use over the last three decades. The contraceptive prevalence rate has tripled since 1968, from 15 to 47 percent of married women. Although contraceptive use has increased since the 1993 NDS (from 40 to 47 percent of married women), comparison with the series of nationally representative Family Planning Surveys indicates that there has been a levelling-off in family planning use in recent years.
Method Mix. Use of traditional methods of family planning has always accounted for a relatively high proportion of overall use in the Philippines, and data from the 1998 NDHS show the proportion holding steady at about 40 percent. The dominant changes in the "method mix" since 1993 have been an increase in use of injectables and traditional methods such as calendar rhythm and withdrawal and a decline in the proportions using female sterilization. Despite the decline in the latter, female sterilization still is the most widely used method, followed by the pill.
Differentials in Family Planning Use. Differentials in current use of family planning in the 16 administrative regions of the country are large, ranging from 16 percent of married women in ARMM to 55 percent of those in Southern Mindanao and Central Luzon. Contraceptive use varies considerably by education of women. Only 15 percent of married women with no formal education are using a method, compared to half of those with some secondary school. The urban-rural gap in contraceptive use is moderate (51 vs. 42 percent, respectively).
Knowledge of Contraception. Knowledge of contraceptive methods and supply sources has been almost universal in the Philippines for some time and the NDHS results indicate that 99 percent of currently married women age 15-49 have heard of at least one method of family planning. More than 9 in 10 married women know the pill, IUD, condom, and female sterilization, while about 8 in 10 have heard of injectables, male sterilization, rhythm, and withdrawal. Knowledge of injectables has increased far more than any other method, from 54 percent of married women in 1993 to 89 percent in 1998.
Unmet Need for Family Planning. Unmet need for family planning services has declined since I993. Data from the 1993 NDS show that 26 percent of currently married women were in need of services, compared with 20 percent in the 1998 NDHS. A little under half of the unmet need is comprised of women who want to space their next birth, while just over half is for women who do not want any more children (limiters). If all women who say they want to space or limit their children were to use methods, the contraceptive prevalence rate could be increased from 47 percent to 70 percent of married women. Currently, about three-quarters of this "total demand" for family planning is being met.
Discontinuation Rates. One challenge for the family planning program is to reduce the high levels of contraceptive discontinuation. NDHS data indicate that about 40 percent of contraceptive users in the Philippines stop using within 12 months of starting, almost one-third of whom stop because of an unwanted pregnancy (i.e., contraceptive failure). Discontinuation rates vary by method. Not surprisingly, the rates for the condom (60 percent), withdrawal (46 percent), and the pill (44 percent) are considerably higher than for the 1UD (14 percent). However, discontinuation rates for injectables are relatively high, considering that one dose is usually effective for three months. Fifty-two percent of injection users discontinue within one year of starting, a rate that is higher than for the pill.
MATERNAL AND CHILD HEALTH
Childhood Mortality. Survey results show that although the infant mortality rate remains unchanged, overall mortality of children under five has declined somewhat in recent years. Under-five mortality declined from 54 deaths per 1,000 births in 1988-92 to 48 for the period 1993-97. The infant mortality rate remained stable at about 35 per 1,000 births.
Childhood Vaccination Coverage. The 1998 NDHS results show that 73 percent of children 12- 23 months are fully vaccinated by the date of the interview, almost identical to the level of 72 percent recorded in the 1993 NDS. When the data are restricted to vaccines received before the child's first birthday, however, only 65 percent of children age 12-23 months can be considered to be fully vaccinated.
Childhood Health. The NDHS provides some data on childhood illness and treatment. Approximately one in four children under age five had a fever and 13 percent had respiratory illness in the two weeks before the survey. Of these, 58 percent were taken to a health facility for treatment. Seven percent of children under five were reported to have had diarrhea in the two weeks preceeding the survey. The fact that four-fifths of children with diarrhea received some type of oral rehydration therapy (fluid made from an ORS packet, recommended homemade fluid, or increased fluids) is encouraging.
Breastfeeding Practices. Almost all Filipino babies (88 percent) are breastfed for some time, with a median duration of breastfeeding of 13 months. Although breastfeeding has beneficial effects on both the child and the mother, NDHS data indicate that supplementation of breastfeeding with other liquids and foods occurs too early in the Philippines. For example, among newborns less than two months of age, 19 percent were already receiving supplemental foods or liquids other than water.
Maternal Health Care. NDHS data point to several areas regarding maternal health care in which improvements could be made. Although most Filipino mothers (86 percent) receive prenatal care from a doctor, nurse, or midwife, tetanus toxoid coverage is far from universal and has been declining somewhat. The proportion of recent births for which the mother reported receiving two or more tetanus toxoid vaccinations during pregnancy declined from 42 in 1993 to 38 percent. Moreover, two-thirds of births in the Philippines are delivered at home; consequently only 56 percent receive asistance at delivery from a doctor, nurse, or midwife and 41 percent are assisted by traditional birth attendants. Proper medical attention during pregnancy and hygienic conditions during delivery can reduce the risk of complications and infections that can cause death or serious illness for either the mother or the newborn. Somewhat more encouraging is the fact that for 75 percent of recent births, mothers reported having received iron tablets during pregnancy and in 57 percent of cases, they received iodine tablets during pregnancy. Maternal mortality has remained low at approximately 200 maternal deaths per 100,000 live births.
HOUSEHOLD HEALTH ISSUES
Health Care Financing. NDHS data indicate that in 40 percent of households, at least one member of the household belongs to a health care financing scheme or an insurance plan. Over 90 percent of such households belong to Medicare.
Knowledge of Herbal Medieines. The Deparmnent of Health has endorsed 10 herbal medicines as being scientifically proven effective for treatment of specific illnesses and conditions. NDHS data show that although awareness of some of these herbs is widespread, knowledge about the specific uses of the herbs is quite limited. For example, although 81 percent of household respondents recognized ampalaya,only one in 20 know that it is useful in treating diabetes and only 6 percent of the 75 percent of respondents who are familiar with sambongcorrectly said that it is used as a diuretic. However, knowledge of bayabasis high; 97 percent of household respondents had heard of it and 81 percent know that it is used to clean wounds.
Knowledge of Healthy Lifestyle. NDHS data indicate quite high general awareness regarding health issues. For example, most household respondents say that they watch their nutrition or exercise to stay healthy. Similarly, a majority of household respondents are aware that smoking causes lung diseases such as cancer. Over 90 percent of respondents have heard of dengue fever and two-thirds of them say that dengue can be prevented by destroying the breeding sites of mosquitos. However, misconceptions about leprosy and tuberculosis abound, with 21 percent of respondents knowing that leprosy is transmitted by skin and 11 percent by airborne droplets, and only one in six respondents knowing that tuberculosis is caused by a germ or bacteria.
Kind of Data
Sample survey data
Unit of Analysis
- Women age 15-49
The 1998 Philippines Demographic and Health Survey covers the following topics:
- Availability of family planning
- Background characteristics (education, religion, etc.)
- Breastfeeding and child health
- Fertility preferences
- Full Pregnancy History
- Knowledge and use of contraception
- Maternal Mortality
- Reproductive history
- Supplies and services
National. The 1998 NDHS aims at providing estimates for each of the sixteen regions of the country.
The population covered by the 1998 Phillipines NDS is defined as the universe of all females age 15-49 years, who are members of the sample household or visitors present at the time of interview and had slept in the sample households the night prior to the time of interview, regardless of marital status.
Producers and sponsors
National Statistics Office (NSO)
Department of Health (DOH)
Macro International, Inc.
U.S. Agency for International Development
Department of Health
University of the Philippine Population Institute (UPPI)
Provider of technical inputs during the preparatory phase
Population Commission (POPCOM)
Provider of technical inputs during the preparatory phase
Food and Nutrition Research Institute (FNRI)
Provider of technical inputs during the preparatory phase
The 1998 NDHS aims at providing estimates for each of the sixteen regions of the country with an acceptable precision for socio-demographic characteristics like fertility, family planning use, and health and mortality indicators. The NDHS sample design consisted of selecting some 12,500 households in 755 enumeration areas (EAs) which was expected to produce completed interviews with approximately 15,000 women age 15-49. The sample was first allocated to each of the regions. Within each region, a self-weighting sampling scheme was adopted; however, due to the non-proportional allocation of the sample to the regions, the NDHS sample is not self-weighting at the national level and weighting factors have been applied to the data.
The 1998 NDHS sample is a sub-sample of the new master sample of the Integrated Survey of Households (ISH) of the NSO. The expanded sample of ISH consists of 3,416 enumeration areas selected from the 1995 census frame with a sophisticated design that allows for regional estimates with periodic rotation of panels. The ISH expanded sample was drawn by first, selecting barangays systematically with probability proportional to size. In barangays that consist of more than one EA, a subsequent step consisted of selecting the sample Elk systematically with probability proportional to size. Because the primary sampling units in the ISH were selected with probability proportional to size, the EAs for the NDHS were sub-selected from the ISH with equal probability to make the NDHS selection equivalent to selection with probability proportional to size. A total of 755 primary sampling units were utilized for the NDHS. Fieldwork in three sample EA was not possible, so a total of 752 EAs Were covered.
The list of households based on the household listing operation conducted in all the NDHS sample points in November 1997 served as the frame for the selection of the NDHS sample households. A different scheme for selecting sample households was applied to urban and rural areas. A systematic sampling of households was carried out in urban areas in order to spread the NDHS sample throughout the sampled EA, while compact clustering was employed in rural areas in order to facilitate field operations. This was accomplished by taking a specified number of consecutive households starting with a household selected at random. Detailed discussion of the 1998 NDHS sampling design is presented in Appendix of the final report.
A total of 13,708 households were selected for the sample, of which 12,567 were occupied. Of these households occupied, 99 percent or 12,407 were successfully interviewed. The shortfall is primarily due to dwellings that were vacant or in which the inhabitants had left for an extended period at the time they were visited by the interviewing teams.
In the households interviewed, 14,390 women were identified as eligible for the individual interview (i.e. age 15-49) and interviews were completed for 13,983 or 97 percent of them. The principal reason for non-response among eligible women was the failure to find them at home despite repeated visits to the household. The refusal rate was low.
Dates of Data Collection
Data Collection Mode
Data Collection Notes
The NDHS questionnaires were pretested in October 1997. Female interviewers were trained at the NSO central office in Manila, after which they conducted interviews in various locations in the field under the observation of staff from NSO central office. Altogether, approximately 160 Household, Woman's and Health Questionnaires were completed. Based on observations in the field and suggestions made by the pretest field teams, revisions were made in the wording and translations of the questionnaires.
Training for the main survey took place in two phases. In the first phase, approximately 35 trainers from NSO, DOH, UPPI, and POPCOM gathered for two weeks in late January at a training center near the NSO central office in Manila. They received thorough training in how to fill and edit the questionnaires, how to supervise fieldwork, and how to train field staff in their respective training sites. These trainers then dispersed to the six training sites (Agoo, Malolos, Lucena City, Cebu City, Iloilo City, and Davao City) where they trained some 261 interviewers, 44 supervisors, and 43 field editors for three weeks (February 9-27, 1998). Initially, training consisted of lectures on how to complete the questionnaires, with mock interviews between participants to gain practice in asking questions. Towards the end of the training course, the participants spent several days in practice interviewing in households near the training sites.
Fieldwork for the NDHS was carried out by 44 interviewing teams. Each team, except that which covered Palawan, Lanao del Sur and Maguindanao, consisted of 1 supervisor, 1 field editor, and 3-7 female interviewers, for a total of 348 field staff. Fieldwork commenced on 3 March 1998 and was completed in the first week of May 1998. Periodic field monitoring of the NDHS operations was done by the NSO regional and provincial officials, NDHS regional supervisors and selected NSO central office staff.
Philippines National Statistics Office (NSO)
There were three types of questionnaires used for the 1998 NDHS: the Household Questionnaire (DHS Form 1), the Individual Questionnaire (NDHS Form 2), and the Health Module (NDHS Form 3). The contents of the first two questionnaires were based on the DHS Model A Questionnaire, which is designed for use in countries with relatively high levels of contraceptive use. These model questionnaires were adapted for use in the Philippines during a series of meetings with representatives from the DOH, UPPI, POPCOM, FNRI, USAID/Philippines, and Macro International Inc. Draft questionnaires were then circulated to other interested groups. These questionnaires were developed in English (see Appendix E) and were translated into six of the most common dialects, namely, Tagalog, Cebuano, Ilocano, Bicol, Hiligaynon, and Waray.
a) The Household (HH) Questionnaire was used to list all the usual members of the sample household, and visitors who slept in the sample household the night prior to the date of interview and some of their characteristics such as name, age, sex, education, relationship to household head, and usual residence. Information on age and sex from the HH Questionnaire was used to identify eligible women for interview using the Individual Questionnaire. Questions about the dwelling such as the source of drinking water, type of toilet facilities, ownership of various consumer goods and use of iodized were also included in the Household Questionnaire.
b) The Individual Questionnaire was used to collect information on the following topics:
- Background characteristics (age, education, religion, etc.)
- Reproductive history and fertility preferences
- Knowledge and use of contraception
- Availability of family planning supplies and services
- Breastfeeding and child health
- Maternal mortality
c) The Health Questionnaire was developed in close collaboration with the DOH in partial substitution for the cancelled National Health Survey, It included questions on health practices of the household, awareness about selected communicable find non-communicable diseases, utilization of and satisfaction with various types of health facilities, knowledge concerning traditional medicines, and health care financing.
Review and editing of NDHS questionnaires was done by the field editors while they were in the enumeration areas to facilitate the verification of the forms. The editors were expected to review questionnaires of at least 8 households per day. The supervisors of teams with more than four interviewers assisted the editors in reviewing the questionnaires.
Folioing of forms was done by the team supervisors before submission to the Provincial Office. The Provincial Statistics Officers were responsible for the transmittal of these forms to the Central Office.
On March 16, 1998, eighteen hired NDHS data processors started the data processing at the Central Office. Office editing, data entry, key verification (100%), and machine processing were done simultaneously. There were two stages involved in the machine processing. In the first stage, keyed-in data were checked for completeness and were matched with the verification data. In the second stage, inconsistencies in the data were noted and checked. All the data processing activities were completed on June 30, 1998.
Estimates of Sampling Error
Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the NDHS is only one of many samples that could have been selected from the same population, using the same design and expected size. Each of these samples would yield results that differ somewhat from the results of the actual sample selected. Sampling errors are a measure of the variability between all possible samples. Although the degree of variability is not known exactly, it can be estimated from the survey results.
In addition to the standard error, ISSA computes the design effect (DEFT) for each estimate, which is defined as the ratio between the standard error using the given sample design and the standard error that would result ira simple random sample had been used. A DEFT value of 1.0 indicates that the sample design is as efficient as a simple random sample, while a value greater than 1.0 indicates the increase in the sampling error due to the use of a more complex and less statistically efficient design. ISSA also computes the relative error and confidence limits for the estimates.
Sampling errors for the NDHS are calculated for selected variables considered to be of primary interest. The results are presented in an appendix to the Final Report for the country as a whole, for urban and rural areas, and for each of the 16 regions. For eanh variable, the type of statistic (mean, proportion, or rate) and the base population are given in Table B. 1 of the Final Report. Tables B.I.1 to B.1.19 present the value of the statistic (R), its standard error (SE), the number of unweighted (N) and weighted (WN) cases, the design effect (DEFT), the relative standard error (SE/R), and the 95 percent confidence limits (Pd:2SE), for each variable. The DEFT is considered undefined when the standard error considering simple random sample is zero (when the estimate is close to 0 or 1). In the case of the total fertility rate, the number of unweighted cases is not relevant since there is no known unweighted value for woman-years of exposure to childbearing.
The confidence interval (e.g., as calculated for children ever born to women age 15-49) can be interpreted as follows: the overall average from the national sample is 2.156 and its standard error is .029. Therefore, to obtain the 95 percent confidence limits, one adds and subtracts twice the standard error to the sample estimate, i.e., 2.156:t:2 x.029. There is a high probability (95 percent) that the true average number of children ever born to all women aged 15 to 49 is between 2.098 and 2.214.
Sampling errors are analyzed for the national sample and for two separate groups of estimates: (1) means and proportions, and (2) complex demographic rates. The relative standard errors (SE/R) for the means and proportions range between 0 percent and 33 percent with an average of 3.6 percent; the highest relative standard errors are for estimates of very low values (e.g., currently using male sterilization among currently married women). If estimates of very low values (less than 10 percent) were removed, than the average drops to 1.8 percent. So in general, the relative standard error for most estimates for the country as a whole is small, except for estimates of very small proportions. The relative standard error for the total fertility rate is small, 2.3 percent. However, for the mortality rates, the average relative standard error is higher, 8.4 percent.
There are differentials in the relative standard error for the estimates of sub-populations. For example, for the variable with secondary education or higher, the relative standard errors as a percent of the estimated mean for the whole country, for the rural areas, and for Cagayan Valley Region are 0.9 percent, 1.8 percent, and 5.4 percent, respectively. For the total sample, the value of the design effect (DEFT) averaged over all variables is 1.27, which means that due to multi-stage clustering of the sample variance is increased by a factor of 1.56 over that in an equivalent simple random sample.
A sampling error is usually measured in terms of the standard error for a particular statistic (mean, percentage, etc.), which is the square root of the variance. The standard error can be used to calculate confidence intervals within which the lrue value for the population can reasonably be assumed to fall. For example, for any given statistic calculated from a sample survey, the value of that statistic will fall within a range of plus or minus two times the standard error of that statistic in 95 percent of all possible samples of identical size and design.
If the sample of respondents had been selected as a simple random sample, it would have been possible to use straightforward formulas for calculating sampling errors. However, the NDHS sample is the result of a two-stage stratified design, and consequently, it was necessary to use more complex formulae. The computer software used to calculate sampling errors for the NDHS is the ISSA Sampling Error Module. This module used the Taylor linearization method of variance estimation for survey estimates that are means or proportions. The Jackknife repeated replication method is used for variance estimation of more complex statistics such as fertility and mortality rates.
Nonsampling errors are the results of mistakes made in implementing data collection and data processing, such as failure to locate and interview the correct household, misunderstanding of the questions on the part of either the interviewer or the respondent, and data entry errors. Although numerous efforts were made during the implementation of the NDHS to minimize this type of error, nonsampling errors are impossible to avoid and difficult to evaluate statistically.
Data and Data Related Resources
National Statistics Office
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