Implementing Bangladesh Demographic and Health Survey S.N. Mitra Md. Shahidul Islam International Workshop on Large Scale National Surveys October 18-19, 2012 Department of Statistics, Rajshahi University

1. Introduction  The Bangladesh Demographic and Health Survey, popularly known as BDHS, is a household based periodical survey conducted 3-4 years apart  Until now, six BDHSs have been implemented. The latest BDHS was done in  BDHS is sponsored by the Ministry of Health and Family Welfare, implemented under the authority of NIPORT with technical support provided by ICF Macro International Inc/USA, and is funded by USAID.  Mitra and Associates implemented all the six surveys under contracts obtained from the ICF Macro International Inc/USA through competitive biddings.

2.Size  BDHS is a large survey operation. It covers the whole of Bangladesh and employs a sample of more than 10,000 households.  It uses five questionnaires: a household questionnaire, a women's questionnaire and a men's questionnaire, a community questionnaire and two verbal autopsy questionnaires—one for death at 0-28days, and one for death at 29 days-59 months).  It requires about an hour to conduct an interview with a respondent.  It is also a complex survey requiring administering of the birth history table, contraceptive table, child immunization table, and contraceptive calendar table.  Besides, the survey involves: a.Measuring height and weight of under-five children and their mothers, b.Obtaining blood pressure measurements, anaemia testing and glucose testing for specific age groups, as well as c.Arsenic testing of household drinking water.

3. Objectives For comparability, major objectives of BDHS are kept unchanged between its different rounds. However, in every round, some new data are collected while excluding the old data considered being no more as important. The usual objectives of BDHS include the following, among others:  To provide up-to-date data on demographic rates, particularly fertility and infant mortality rates at the national and subnational level;  To measure the level of contraceptive use of currently married women;  To assess the nutritional status of children under age 5, women and men by means of anthropometric measurements (weight and height), and to assess infant and child feeding practices;  To provide data on maternal and child health, including antenatal care, assistance at delivery, breastfeeding, immunizations, etc.  And to provide measures of the factors that determine the level of and trends in the above parameters

4. Sample Design BDHS sample is a nationally representative, probability sample of households.  It is drawn in two stages, stratifying the country by rural and urban areas and the divisions of the country.  A Census Enumeration Area (EA), created to have an average of 120 households, is used as the Primary Sampling Unit (PSU).  In latest BDHS (namely 2011 BDHS), 600 EAs were selected in the first stage as the sample clusters, with 207 included from urban areas and 393 from rural areas.  EAs from each stratum are selected independently with Probability Proportional to the EA size (PPS method).  In order to have a sampling frame for selection of households at the second stage, households in every selected EA (cluster) are listed, making house-to-house visits.

 Thirty households are systematically selected from a cluster to yield the total sample for a survey.  Thus, a total sample of 18,000 households were selected in the 2011 BDHS, including 11,790 from rural areas and 6,210 from urban areas. (NIPORT et al., 2012).  In order to provide separate estimates for both the rural and urban areas as well as for each of the divisions, the small divisions are over sampled compared to the other divisions, as are the urban areas compared to the rural areas.  Thus the BDHS sample is not self-weighting. Weighting of the sample is therefore needed to generate aggregate level estimates.

5. Respondents Two categories of respondents are interviewed in the BDHS.  One category consists of ever-married women age 10-49, and one category of ever-married men age  While all ever-married women in every household included in the sample are considered as eligible respondents to be interviewed in the survey, interviews with ever-married men are conducted in only a sub-sample of the sample households.  In 2011 BDHS, for example, ever-married men were interviewed in a sub- sample of one-third of the sample households.

6. Preparation of Questionnaires There are a number of steps involved in the preparation of the BDHS' questionnaires.  The questionnaires are first drafted by using the MEASURE DHS Model Questionnaires.  The drafts are then modified by the Technical Work Group (TWG) to make the questionnaires appropriate to the Bangladesh's situations, by adding and deleting questions as needed.  The questionnaires are prepared in English.  The implementing agency (Mitra and Associates) translates them into Bengali.  Translations back to English are done to verify the accuracy of the Bengali translations.

 The draft questionnaires pre-tested in two urban areas and two rural areas.  The purpose of the pretest is to check the translation, consistency and integrity of the questionnaires.  A minimum of 200 households is interviewed in the pretest, with 50 households covered from each pretest- area.  Based on the pretest results, the questionnaires are finalized, making the necessary modifications by TWG, IFC Macro and Mitra and Associates.

7.Household Listing Operation  Household listing operation is carried out usually in four phases, with a phase usually spanning over three weeks.  For example, in 2011 BDHS, initially 19 teams of listers (later reduced to 15 teams) were deployed for four months for the listing operation. A listing team consisted of two listers.  In addition, 6 listing supervisors were deployed to check and verify the work of the listing teams.

8. Data Collection Operation  In the BDHS, data collection work is carried out in phases, deploying several interviewing teams.  In the 2011 BDHS, 16 interviewing teams were deployed to complete the data collection work in five phases, with a phase spanning over three weeks.  An interviewing team is composed of a male supervisor, a female supervisor/editor, four female interviewers, two male interviewers, and a logistical assistant.  Four quality control teams are employed for quality control checking of the data. A quality control team includes a male quality control officer and a female quality control officer.

9.Monitoring of Fieldwork Monitoring of fieldwork is a key tool of BDHS to ensure collection of quality data  As soon as completed questionnaires for a phase are received and registered in the tracking register, some key information from the questionnaire is entered into the computer.  The key information usually chosen includes such variables as household result code, number of eligible respondents, individual result code, respondent's age, marital status, number of children born in the last five years, current contraceptive use status, knowledge of contraceptive method, ever use status, etc.  The 'key information' entry is completed in 3/4 days.  The key information is then tabulated by rural-urban area, by division, by team, and by interviewer.  The findings are shared with the interviewing teams in the debriefing session held one/two days before the teams are sent out for the next phase.

 In the debriefing session, the results of the 'key information' tables are discussed in detail, by team and by interviewer.  Interviewers having relatively high non-response rates are asked to explain why they had more non-response cases than the others. The explanations are also sought from their supervisors. The quality control officers who had checked the work of the interviewers are also asked to give their views regarding the interviewers' questionable performances.  Similarly, the results for every other key variable are discussed in the debriefing session.  In the process, the survey management team identifies the supervisors and interviewers who require further training/instructions for improvement of their performances.  If anyone is found to have been dishonest, he/she is terminated from the service.  Benefit of the monitoring of interviewing performances is enormous. Every interviewer, supervisor and quality control officer would know that there is a way of checking every body's work.  Because of this awareness, most people engaged in the survey are expected to work diligently to obtain accurate data.

10. Training BDHS’s field personnel (listers, interviewers, supervisors and quality control officers) are provided adequate training to prepare them for the survey work.  Training on household listing operation for listers is conducted for 7 working days, while training on data collection operation for the field personnel (interviewers, supervisors and quality control officers) is conducted for three weeks.  Training consists of lectures, classroom practices, group discussions and role-playing. At the conclusion of the training, a test is taken to see if the trainees have achieved the knowledge and skills required to work in the survey.  Those who cannot pass the test are not employed.

11. Data Management/Report Writing This task is carried out in several steps.  As soon as questionnaires from the field are received at the office, they are registered in the registration book. One registration officer is employed to do the registration work, and store and maintain the questionnaires. He also supplies the questionnaires for use by the data processing staff and receives these records back when their use is over.  Data are entered and processed using the computer facility of Mitra and Associates and by employing the statistical package program, CSPro, supplied by ICF Macro.  After the data are cleaned, Mitra and Associates produces the tables for the report. The clean data set and the tables are then submitted to ICF Macro for the preparation of the report.

12. Quality of Fieldwork  High response rates are a key indicator of BDHS’s excellent field work, and hence, of its data quality.  As shown in Table 1, out of 17,511 occupied households in the 2011 BDHS sample, 17,141 were successfully interviewed, achieving a household response rate of 98% nationally.  Individual response rates were as high for women at 98% nationally; they were also over 90% nationally for men, who are relatively less available at home than women.  There were little variations in the response rates between rural and urban areas.  Response rates were also high in the other BDHSs, upholding the excellent fieldwork as a salient characteristic of the BDHS.

InterviewsRural AreasUrban AreasNational Household interviews97.2 (11,476)98.2 (6,035)97.9 (17,511) Interviews with Ever-married women age (6,390) 98.4 (11,832) 97.9 (18,222) Interviews with Ever-married men age (1,586) 92.9 (2,757) 92.0 (4,343) Table 1: Response Rates in 2011 BDHS

13. Reliability of Estimates Estimates from the BDHS were generally found to be statistically reliable.  For example, as shown in Table 2, in the 2007 BDHS, the TFR (Total Fertility Rate) per women was estimated as within error margins of +/ at the 95% confidence level in the national sample;  as within error margins of +/ in the rural sample and as within error margins of +/ in the urban sample;  the CPR (Contraceptive Prevalence Rate) per 100 currently married women was estimated as 55.8 within error margins of +/ at the 95% confidence level in the national sample;  as 54.0 within error margins of +/ in the rural sample and as 62.0 within error margins of +/-2.40 in the urban sample;  Similar evidence of stability was apparent for the estimates from the other BDHS surveys.

ParameterEstimateStandard Error (SE) 95% Confidence Limits Lower BoundUpper Bound TFR National Rural Urban CPR National Rural Urban Table 2: Sampling Errors of the Total Fertility Rate (TFR) and Contraceptive Prevalence Rate, in BDHS 2007

 Another evidence of reliability of BDHS estimates was apparent in the comparison of the population age distribution between the two consecutive surveys.  With the fertility and mortality declining, the age distribution changes, but the changes, being gradual and small, are unlikely to make the distribution discernibly different between the two consecutive surveys done 3-4 years apart.  Thus, the similarity of the age distribution obtained from the 2005 BDHS survey with that from the 2009 BDHS survey, shown in Figure1, confirms the reliability of the BDHS estimates.

Figure 1: Comparison of the Population Age distribution between BDHS 2004 and BDHS 2007

 Reliability of BDHS estimates was also apparent in the comparison of the TFR and CPR estimates at the divisional level;  As shown in Figure, in the 2011 BDHS, among the divisions of the country, the lowest TFR at was associated with the highest CPR per 100 women at in the Rajshahi and Khulna divisions;  and the highest TFR at 3.7 associated with the lowest CPR at 32 in the Sylhet division;  Again, the Barisal and Dhaka divisions, both, had the same TFR at 2.8, with both having the same CPR at 56;  Contraceptive use is a major determinant of fertility in Bangladesh. Thus, the fertility and contraceptive data were found internally consistent in the 2011 BDHS showing higher TFR in a division where CPR was lower or vice versa;  Attesting to the credibility of the data, such internal consistencies were also notable in the other BDHS surveys.

Figure 2: Comparison of Total Fertility Rate and Contraceptive Prevalence Rate by Division in the BDHS 2007

13.Conclusion  Professionally implemented with utmost care, BDHSs have emerged as credible sources of population and health data for policy makers and program managers (MOHFW, 2011).  If BDHS’s experiences are further refined and used, survey taking capabilities would doubtless improve in the country.

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