PHL_1993_DHS_v01_M
National Demographic Survey 1993
Resultados de la Encuesta Demographica y salud Familiar Peru 2000 1993
Name | Country code |
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Philippines | PHL |
Demographic and Health Survey (standard) - DHS III
The 1993 Philippines Demographic and Health Survey (PDHS) is the sixth DHS survey carried out every five years since 1968 in order to measure trends in demographic and family planning indicators in Philippines. But the 1993 NDHS is the first national sample survey undertaken in Philippines under the auspices of the worldwide Demographic and Health Surveys program.
Sample survey data
The 1993 Philippines Demographic and Health Survey covers the following topics:
National. The main objective of the 1993 NDS sample is to allow analysis to be carried out for urban and rural areas separately, for 14 of the 15 regions in the country. Due to the recent formation of the 15th region, Autonomous Region in Muslim Mindanao (ARMM), the sample did not allow for a separate estimate for this region.
The population covered by the 1993 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 |
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National Statistics Office (NSO) |
Name | Role |
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Macro International, Inc. | Technical assistance |
Department of Health (DOH) | Collaborator |
Name | Role |
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U.S. Agency for International Development | Funding |
Name | Affiliation | Role |
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Population Institute | University of the Philippines (UP) | Technical assistance |
The main objective of the 1993 National Demographic Survey (NDS) sample is to provide estimates with an acceptable precision for sociodemographics characteristics, like fertility, family planning, health and mortality variables and to allow analysis to be carried out for urban and rural areas separately, for 14 of the 15 regions in the country. Due to the recent formation of the 15th region, Autonomous Region in Muslim Mindanao (ARMM), the sample did not allow for a separate estimate for this region.
The sample is nationally representative with a total size of about 15,000 women aged 15 to 49. The Integrated Survey of Households (ISH) was used as a frame. The ISH was developed in 1980, and was comprised of samples of primary sampling units (PSUs) systematically selected and with a probability proportional to size in each of the 14 regions. The PSUs were reselected in 1991, using the 1990 Population Census data on population size, but retaining the maximum number of PSUs selected in 1980.
This sample is self-weighted in each of the 14 regions, but not at the national level. It was selected using a two-stage sample design; the first involved the selection of barangays,and the second, the selection of households in the sampled barangays. Barangays are the smallest political subdivisions. In general, the barangay corresponds to a census enumeration area. However, they vary widely in size, some covering more than 1,000 households. In the case when the barangay size was very large, it was segmented into several enumeration areas.
To maximize the efficiency of the sample design, the sample was allocated to the regions using a method called "power allocation procedure." This method optimizes the precision by taking into account sampling errors found in previous demographic surveys, in particular the 1978 Republic of the Philippines Fertility Survey. For this purpose, the following characteristics were considered: mean number of children ever born, proportion of women who want no more children, mean number of children desired, and proportion of married women who are using a family planning method.
A total of 2100 PSUs were selected for ISH, 750 of which were selected for the 1993 NDS. Individual households were selected with a probability of selection inversely proportional to the barangay's size to maintain a fixed overall sampling fraction within each region. An average of 20 completed interviews was targeted in each PSU.
In total, 750 PSUs and about 13,700 households were selected. The survey was well received by the respondents. Response rate for the household interview varies slightly by region (see Table A. 1). In some regions, all of the households in the sample were successfully interviewed. For the individual women's interview, Bicol women have the lowest overall response rate (93 percent).
A total of 15,029 women aged 15-49 years were successfully interviewed. The weighting factors to provide national estimates were calculated as the inverse of the overall sampling fractions, adjusted with the corresponding household and individual responses rates.
The household interviews identified 15,332 eligible women. Of these, 15,029 were successfully interviewed, giving a response rate of 98 percent. The principal reason for nonresponse among eligible women was the failure of interviewers to find them at home despite repeated visits to the household. Refusals were few in number (less than one percent).
A total of 13,728 households was selected for the survey, of which 12,995 were successfully interviewed. The difference was due to one of the following reasons: some selected households had moved out or could not be located by the NDS team; there were no eligible respondents found for the selected household during the NDS team's visit; or the household simply refused to be interviewed.
Three types of questionnaires were used for the 1993 NDS: the Household Questionnaire, the Individual Woman's Questionnaire and the Service Availability Questionnaire. The contents of the first two questionnaires were based on the DHS Model Questionnaire, which was designed for use in countries with high levels of contraceptive use. Additions and modifications to the model questionnaires were made after consultation with members of a Technical Working Group convened for the purpose of providing technical assistance to the NSO in the implementation of the survey.
The household and individual questionnaires were developed in English and then translated into and printed in six of the most widely spoken languages in the Philippines, namely: Tagalog, Cebuano, Ilocano, Hiligaynon, Bicol and Waray.
a) The Household Questionnaire was used to list all the usual members and visitors of selected households. Some basic information was collected on the characteristics of each person listed, including his/her age, sex, education, and relationship to the head of the household. The main purpose of the Household Questionnaire was to identify women who were eligible for individual interview. In addition, information was collected about the dwelling, such as the source of water, type of toilet facilities, materials used for the floor of the house, and ownership of various consumer goods.
b) The Individual Woman's Questionnaire was used to collect information from women aged 15-49. An important change from the past practice in large-scale demographic surveys in the Philippines is that the 1993 NDS covered all women 15-49 instead of limiting the interview to ever-married women. In keeping with past practice, the questionnaire contained a pregnancy history instead of the usual DHS birth history. Women were asked questions on the following topics:
c) The Health Service Availability Questionnaire was designed to collect information about health and family planning services available to the individual women respondents. This questionnaire was administered at the cluster level, that is, one questionnaire was filled for each of the 750 sample points. Combined with information collected in the main survey, data from the two surveys can identify subgroups of women who are underserved by the health and family planning providers.
Start | End |
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1993-03 | 1993-05 |
Name |
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Philippines National Statistics Office (NSO) |
During the first two weeks of the field work, statisticians from the Central Office, who served as trainers during the training of interviewers, went on field trips to observe and guide the teams in their initial interviews.
The 1993 NDS questionnaires were pretested in December 1992. Three pretest areas were selected; namely, the barangays of Malolos and Calumpit, Bulacan Province, and Barangay Tatalon in Metropolitan Manila. Fifteen female interviewers were recruited. Three NSO employees were assigned as field editors, and three statisticians from the NSO were assigned to supervise the fieldwork. About 180 interviews of women 15-49 were completed in the pretest. The pretest results were used as basis for revising the questionnaires and the translations into the six dialects. They also provided a basis for firming up survey operational procedures.
Training of field staff for the main survey was conducted in the following designated training sites: Baguio City, Manila, Cebu City and Davao City. The training course consisted of instructions in general interviewing techniques, field procedures, a detailed review of items on the questionnaires, mock interviews between participants in the classroom, and practice interviews in the field. Trainees who performed satisfactorily in the training program were selected as interviewers, while those whose performance was rated as superior were selected as field editors.
The fieldwork for the Philippine NDS was carried out by 31 interviewing teams. Each team consisted of one team supervisor, one field editor, and an average of five interviewers. The Regional Administrators of NSO served as field coordinators during the data collection phase of the survey.
Editing of the questionnaires was an integral part of the field data collection in the sense that questionnaires based on successful interviews were immediately edited by field editors. Further review and coding of some variables were done at the NSO central office. Machine processing was also done at the central office.
Processing of the NDS data was done with the use of the DHS computer program ISSA (Integrated System for Survey Analysis), from data entry to tabulation. Seven microcomputers were made available by NSO for data entry while Macro International provided four microcomputers for data management as well as for running edit and tabulation programs. Initial tabulations were generated by the end of August 1993, and a preliminary report was released in October 1993.
Sampling errors, on the other hand, can be measured statistically. The sample of women selected in the 1993 NDS is only one of many samples that could have been selected from the same population, using the same design and expected size. Each one would have yielded results that differed somewhat from the actual sample selected. The sampling error is a measure of the variability between all possible samples; although it is not known exactly, it can be estimated from the survey results.
Sampling error is usually measured in terms of standard error of 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, apart from nonsampling errors, the true 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 same statistic as measured in 95 percent of all possible samples with the same design (and expected size) will fall within a range of plus or minus two times the standard error of that statistic.
If the sample of women had been selected as a simple random sample, it would have been possible to use straightforward formulas for calculating sampling errors. However, the 1993 NDS sample was designed using stratification (region and urban/rural), clustering (barangay or a segment thereof) and stages of selection (barangay and household on the first and second stage, respectively). Consequently, it was necessary to utilize more complex formulas. The module on sampling errors in the ISSA package developed for the Demographic and Health Surveys program was used to assist in computing the sampling errors with the proper statistical methodology.
In addition to the standard errors, the program 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 ifa 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. The ISSA program also computes the relative error and confidence limits for the estimates.
For each variable, the type of statistic (mean or proportion) and the base population are given in Table B.1 of the Final Report. Sampling errors are presented in Tables B.2.1-B.2.17 of the Final Report for variables considered to be of major interest. Results are presented for the whole country, divided into urban and rural areas, and for each of the 14 regions. For each variable, Tables B.2.1-B.2.17 present the value of the statistic (R), its standard error (SE), the number of unweighted (N) and weighted cases (WN), the design effect (DEFT), the relative standard error (SE/R), and the 95 percent confidence limits (R+2SE).
More complex estimates like the total fertility rate, infant mortality rate or medians are calculated using the Jackknife replication procedure incorporated in this ISSA module. Results are presented only for the whole country, divided into urban and rural areas, but not for each of the 14 regions, because these estimates need to have a large sample size to provide accurate precision.
The confidence limits have the following interpretation. For the proportion of married women currently using a contraceptive method (currently using any method), the overall average from the sample is 0.400 and its standard error is 0.006. Therefore, to obtain the 95 percent confidence limits, one adds and subtracts twice the standard error to the sample estimate, i.e., 0.400 + (2 x 0.006), which means that there is a high probability (95 percent) that the true proportion currently using is between 0.387 and 0.412.
The relative standard error for most estimates for the country as a whole is small, except for estimates of very small proportions. The magnitude of the error increases as estimates for subpopulations such as geographical areas are considered. For the variable currently using any method, for instance, the relative standard error (as a percentage of the estimated proportion) for the whole country and for urban and rural areas is 1.5 percent, 2.1 percent, and 2.3 percent, respectively.
Nonsampling error is due to mistakes made in carrying out field activities, such as failure to locate and interview the correct household, errors in the way the questions are asked, misunderstanding on the part of either the interviewer or the respondent, data entry errors, etc. Although efforts were made during the design and implementation of the 1993 NDS to minimize this type of error, nonsampling errors are impossible to avoid and difficult to evaluate statistically.
Name | Affiliation | URL | |
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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 | |
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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_1993_DHS_v01_M
Name | Role |
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World Bank, Development Economics Data Group | Generation of DDI documentation |
2012-05-02
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