The 2005 Cambodia Demographic and Health Survey (CDHS) uses the same methodology as its predecessor, the 2000 Cambodia Demographic and Health Survey, allowing policymakers to use the two surveys to assess trends over time.
The primary objective of the CDHS is to provide the Ministry of Health, Ministry of Planning (MOP), and other relevant institutions and users with updated and reliable data on infant and child mortality, fertility preferences, family planning behavior, maternal mortality, utilization of maternal and child health services, health expenditures, women’s status, domestic violence, and knowledge and behavior regarding HIV/AIDS and other sexually transmitted infections. This information contributes to policy decisions, planning, monitoring, and program evaluation for the development of Cambodia, at both national- and local-government levels.
The long-term objectives of the survey are to technically strengthen the capacity of the National Institute of Public Health (NIPH), Ministry of Health, and the National Institute of Statistics (NIS) of MOP for planning, conducting, and analyzing the results of further surveys.
The 2005 DHS survey was conducted by the National Institute of Public Health (NIPH), the Ministry of Health, and the National Institute of Statistics of the Ministry of Planning. The CDHS executive committee and technical committee were established to oversee all technical aspects of implementation. They consisted of representatives from the Ministry of Health, the National Institute of Public Health, Department of Planning and Health Information, the Ministry of Planning, the National Institute of Statistics, the U.S. Agency for International Development (USAID), Department for International Development (DFID), the United Nations Population Fund (UNFPA), and the United Nations Children’s Fund (UNICEF). Funding for the survey came from USAID, the Asian Development Bank (ADB) (under the Health Sector Support Project HSSP, using a grant from the United Kingdom, DFID), UNFPA, UNICEF, and the Centers for Disease Control/Global AIDS Program (CDC/GAP). Technical assistance was provided by ORC Macro.
Kind of data
Sample survey data
Unit of analysis
- Children under five years
- Women age 15-49
- Men age 15-49
Producers and sponsors
National Institute of Public Health
Ministry of Health
National Institute of Statistics
Ministry of Planning
United State Agency for International Development
United Nations Children’s Fund
Department for International Development
Asian Development Bank
United Nations Population Fund
Centers for Disease Control
Global AIDS Program
Creation of the 2005 CDHS sample was based on the objective of collecting a nationally representative sample of completed interviews with women and men between the ages of 15 and 49. To achieve a balance between the ability to provide estimates for all 24 provinces in the country and limiting the sample size, 19 sampling domains were defined, 14 of which correspond to individual provinces and 5 of which correspond to grouped provinces.
- Fourteen individual provinces: Banteay Mean Chey, Kampong Cham, Kampong Chhnang, Kampong Speu, Kampong Thom, Kandal, Kratie, Phnom Penh, Prey Veng, Pursat, Siem Reap, Svay Rieng, Takeo, and Otdar Mean Chey;
- Five groups of provinces: Battambang and Krong Pailin, Kampot and Krong Kep, Krong Preah Sihanouk and Kaoh Kong, Preah Vihear and Steung Treng, Mondol Kiri, and Rattanak Kiri.
The sample of households was allocated to the sampling domains in such a way that estimates of indicators can be produced with known precision for each of the 19 sampling domains, for all of Cambodia combined, and separately for urban and rural areas of the country.
The sampling frame used for 2005 CDHS is the complete list of all villages enumerated in the 1998 Cambodia General Population Census (GPC) plus 166 villages which were not enumerated during the 1998 GPC, provided by the National Institute of Statistics (NIS). It includes the entire country and consists of 13,505 villages. The GPC also created maps that delimited the boundaries of every village. Of the total villages, 1,312 villages are designated as urban and 12,193 villages are designated as rural, with an average household size of 161 households per village.
The survey is based on a stratified sample selected in two stages. Stratification was achieved by separating every reporting domain into urban and rural areas. Thus the 19 domains were stratified into a total of 38 sampling strata. Samples were selected independently in every stratum, by a two stage selection. Implicit stratifications were achieved at each of the lower geographical or administrative levels by sorting the sampling frame according to the geographical/administrative order and by using a probability proportional to size selection at the first stage of selection.
In the first stage, 557 villages were selected with probability proportional to village size. Village size is the number of households residing in the village. Some of the largest villages were further divided into enumeration areas (EA). Thus, the 557 CDHS clusters are either a village or an EA. A listing of all the households was carried out in each of the 557 selected villages during the months of February-April 2005. Listing teams also drew fresh maps delineating village boundaries and identifying all households. These maps and lists were used by field teams during data collection.
The household listings provided the frame from which the selection of household was drawn in the second stage. To ensure a sample size large enough to calculate reliable estimates for all the desired study domains, it was necessary to control the total number of households drawn. This was done by selecting 24 households in every urban EA, and 28 households in every rural EA. The resulting oversampling of small areas and urban areas is corrected by applying sampling weights to the data, which ensures the validity of the sample for all 38 strata (urban/rural, and 19 domains).
All women age 15-49 years who were either usual residents of the selected households or visitors present in the household on the night before the survey were eligible to be interviewed. In addition, in a subsample of every second household selected for the survey, all men age 15-49 were eligible to be interviewed (if they were either usual residents of the selected households or visitors present in the household on the night before the survey). The minimum sample size is larger for women than men because complex indicators (such as total fertility and infant and child mortality rates) require larger sample sizes to achieve sampling errors of reasonable size, and these data come from interviews with women.
In the 50 percent subsample, all men and women eligible for the individual interview were also eligible for HIV testing. In addition, in this subsample of households all women eligible for interview and all children under the age of five were eligible for anemia testing. These same women and children were also eligible for height and weight measurement to determine their nutritional status. Women in this same subsample were also eligible to be interviewed with the cause of death module, applicable to women with a child born since January 2002.
The 50 percent subsample not eligible for the man interview was further divided into half, resulting in one-quarter subsamples. In one-quarter subsample all women age 15-49 were eligible for the woman's status module in addition to the main interview. In this same one-quarter subsample, one woman per household was eligible for the domestic violence module. In the other one-quarter subsample, women were not eligible for the woman's status module, nor the domestic violence module.
NOTE: See detailed description of the sample design in APPENDIX A of tthe survey report.
All of the 557 clusters selected for the sample were surveyed in the 2005 CDHS. A total of 15,046 households were selected, of which 14,534 were identified and occupied at the time of the survey. Among these households, 14,243 completed the Household Questionnaire, yielding a response rate of 98 percent.
In the 14,243 households surveyed, 17,256 women age 15-49 years were identified as being eligible for the individual interview. Interviews were completed with 16,823 of these women, yielding a response rate of 98 percent. Interviews with men were conducted in every second household. A total of 7,229 men age 15-49 years were identified in the subsample of households. Of these 7,229 men, 6,731 completed the individual interview, yielding a response rate of 93 percent.
Note: See summarized response rates by residence (urban/rural) in Table 1.1 of the survey report.
Dates of collection
Mode of data collection
Three questionnaires were used: the Household Questionnaire, Woman Questionnaire, and Man Questionnaire. The content of these questionnaires was based on model questionnaires developed by the MEASURE DHS project. Technical meetings between experts and representatives of the Cambodian government and national and international organizations were held to discuss the content of the questionnaires. Inputs generated by these meetings were used to modify the model questionnaires to reflect the needs of users and relevant population, family planning, and health issues in Cambodia. Final questionnaires were translated from English to Khmer and a great deal of refinement to the translation was accomplished during the pretest of the questionnaires.
The Household Questionnaire served multiple purposes:
- It was used to list all of the usual members and visitors in the selected households and was the vehicle for identifying women and men who were eligible for the individual interview.
- It collected basic information on the characteristics of each person listed, including age, sex, education, and relationship to the head of the household.
- It collected information on characteristics of the household’s dwelling unit, ownership of various durable goods, ownership and use of mosquito nets, and testing of salt for iodine content.
- It collected anthropometric (height and weight) measurements and hemoglobin levels.
- It was used to register people eligible for collection of samples for later HIV testing.
- It had a module on recent illness or death.
- It had a module on utilization of health services.
The Women’s Questionnaire covered a wide variety of topics divided into 13 sections:
- Respondent Background
- Reproduction, including an abortion module
- Family Planning
- Pregnancy Postnatal Care and Children’s Nutrition
- Immunization Health and Women’s Nutrition
- Cause of Death of Children (also known as Verbal Autopsy)
- Marriage and Sexual Activity
- Fertility Preferences
- Husband’s Background and Woman’s Work
- HIV AIDS and Other Sexually Transmitted Infections
- Adult and Maternal Mortality
- Women’s Status
- Household Relations (also known as Domestic Violence)
The Men’s Questionnaire was administered to all men age 15-49 years living in every second household of the 2005 CDHS sample. The Man Questionnaire collected information similar to that of the Woman Questionnaire but was shorter as it did not contain as detailed a reproductive history, or questions on maternal and child health, or nutrition.
The CDHS underwent a full pretest in May 2005. Twenty four women and 23 men were trained in the administration of the CDHS survey instruments and blood collection techniques. Training and fieldwork included the Household Questionnaire, (not including anthropometry or testing of salt for iodine), the full 13 sections of the Woman Questionnaire, and the full Man Questionnaire. The training course was followed by five days of interviewing and blood collection, and a full day of interviewer debriefing. Constructive inputs of interviewers were used to refine survey instruments and logistics. Questionnaires were finalized as a result of pretest activities.
Data entry on 19 personal computers began on 22 September 2005, just two weeks after the first interviews were being conducted. Data entry personnel attended questionnaire training of interviewers so as to become familiar with the survey instruments. Data processing personnel included a data processing chief, four assistants, 19 entry operators, and three office editors. Completed questionnaires were brought in from the field by survey coordinators and questionnaires and anonymous blood samples were logged by the office editors. Once proper accounting of questionnaires and blood samples was accomplished on a per-cluster basis, blood samples were transported to the NIPH laboratory for later testing. Questionnaire data were entered at NIS using CSPro, a program developed jointly by the United States Census Bureau, the ORC Macro MEASURE DHS program, and Serpro S.A. All questionnaires were entered twice to minimize data entry error. Data entry was completed in April 2006. Internal consistency verification and secondary editing were completed in May 2005.
The estimates from a sample survey are affected by two types of errors: (1) nonsampling errors, and (2) sampling errors. 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 2005 Cambodia Demographic and Health Survey (CDHS) to minimize this type of error, nonsampling errors are impossible to avoid and difficult to evaluate statistically.
Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the 2005 CDHS 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.
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 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 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 2005 CDHS sample is the result of a multi-stage stratified design, and, consequently, it was necessary to use more complex formulae. The computer software used to calculate sampling errors for the 2005 CDHS is a Macro SAS procedure. This procedure used the Taylor linearization method for 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.
Note: See detailed estimate of sampling error calculation in APPENDIX B of tthe survey report.
Other forms of data appraisal
Data Quality Tables
- Household age distribution
- Age distribution of eligible and interviewed women
- Age distribution of eligible and interviewed men
- Completeness of reporting
- Births by calendar years
- Reporting of age at death in days
- Reporting of age at death in months
NOTE: See detailed in APPENDIX C of the report which is presented in this documentation.
Use of the survey microdata should be acknowledged using a citation in which the producer, depositor, survey name and date of download are provided, e.g.:
National Institute of Public Health, National Institute of Statistics [Cambodia] and ORC Macro. 2006. Cambodia Demographic and Health Survey 2005. Ref. KHM_2005_DHS_v01_M. Survey dataset downloaded from www.measuredhs.com on [date]
Disclaimer and copyrights
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.