PHL_1998_DHS_v01_M
National Demographic and Health Survey 1998
Name | Country code |
---|---|
Philippines | PHL |
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.
Sample survey data
The 1998 Philippines Demographic and Health Survey covers the following topics:
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.
Name |
---|
National Statistics Office (NSO) |
Department of Health (DOH) |
Name | Role |
---|---|
Macro International, Inc. | Technical assistance |
Name | Role |
---|---|
U.S. Agency for International Development | Funding |
Department of Health | Funding |
Name | Role |
---|---|
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.
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:
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.
Start | End |
---|---|
1998-02 | 1998-04 |
Name |
---|
Philippines National Statistics Office (NSO) |
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.
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.
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.
Name | Affiliation | URL | |
---|---|---|---|
MEASURE DHS | ICF International | www.measuredhs.com | archive@measuredhs.com |
Use of the dataset must be acknowledged using a citation which would include:
The user of the data acknowledges that the original collector of the data, the authorized distributor of the data, and the relevant funding agency bear no responsibility for use of the data or for interpretations or inferences based upon such uses.
Name | URL | |
---|---|---|
General Inquiries | info@measuredhs.com | www.measuredhs.com |
Data and Data Related Resources | archive@measuredhs.com | www.measuredhs.com |
National Statistics Office | info@mail.census.gov.ph | http://www.census.gov.ph/ |
DDI_PHL_1998_DHS_v01_M
Name | Role |
---|---|
World Bank, Development Economics Data Group | Generation of DDI documentation |
2012-05-02
This site uses cookies to optimize functionality and give you the best possible experience. If you continue to navigate this website beyond this page, cookies will be placed on your browser. To learn more about cookies, click here.