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Nutritional Surveillance Project, Bangladesh

Since its inception in 1990, the Nutritional Surveillance Project (NSP) of Helen Keller International (HKI) and the Institute of Public Health Nutrition (IPHN), Government of Bangladesh, has been an independent source of high-quality data on the health and nutrition of children and women in Bangladesh. The NSP was originally designed to monitor the impact of disasters and the effectiveness of relief and rehabilitation programs in disaster-prone areas of Bangladesh. While this role has continued, information generated by the NSP over the last 16 years has helped inform policymakers, program managers and donor organizations on many development concerns in the country, including health, nutrition, food security, homestead food production, gender disparities, and rural and urban poverty.

The NSP collects information from children aged less than five years, their mothers and their households throughout rural Bangladesh and in the urban slums of the six largest cities in the country. These data are collected by IPHN and NGO partners with supervision, quality control and data analysis by HKI. Data collection takes place every two months to capture seasonal changes in nutrition and health. This allows the impact of disasters, programs and policies to be distinguished from seasonal effects. It also makes the NSP better prepared to assess the impact of a disaster or other crisis event because data are collected a maximum of two months before and after an event and therefore the magnitude of any change can be more accurately assessed. NSP data collected on over 930,000 households in the last 16 years can be used to monitor long-term trends, and to measure the impact of programs and policies against any underlying secular trends.

NSP data collection 
NSP data collection sites

The NSP currently collects data in 28 rural sub-districts (upazila), four in each of the six divisions as well as in the Chittagong Hill Tracts, and in urban slums in Barisal, Chittagong, Dhaka, Khulna, Rajshahi and Sylhet. See the map of the NSP data collection sites.

Frequency and timing of data collection Since its inception in 1990, the NSP has conducted Ďroundsí of data collection every two months in February, April, June, August, October and December. The rounds are timed to coincide with the six seasons in Bangladesh. Each round of data collection takes seven to eight weeks to complete. The rounds are numbered consecutively, beginning with the first round in April 1990. The months of data collection and the corresponding season for the rounds in 2005 are given in Table 1.
     
Table 1. Months of data collection and the corresponding season for the six rounds of NSP data collection in 2005
  

 

Round of data collection Months of data collection Name of season

 

90 February - March Spring (Bashonto)

 

91 April - May Summer (Grishmo)

 

92 June - July Rainy season (Borsha)

 

93 August - September Pre-Autumn (Sharot)

 

94 October - November Late Autumn (Hemonto)

 

95 December - January Winter (Sheeth)
Sampling

For each round of data collection, a new sample of 10,500 households in rural Bangladesh and 1,500 households in the urban slum sites is selected. A household is eligible for inclusion if it contains at least one physically abled child aged less than 5 years and if the mother is present. Sampling strategies differ for the rural and urban slum samples.

Rural Bangladesh  

 

The current stratified multi-stage cluster sampling design was introduced in February 1998 and provides data that are statistically representative at the divisional and national levels. Data are collected from four sub-districts in each of the six divisions of the country as well as the Chittagong Hill Tracts (CHT). The divisional sub-districts were randomly selected when the sampling design was introduced, the CHT sub-districts were newly selected in 2003. NSP sub-districts remain the same from round to round. For each round of data collection, 15 mauza (administrative unit within a sub-district) are randomly selected from each of the four sub-districts. One village is randomly selected from each mauza, and 25 households are systematically sampled from each village. Therefore the total number of households in each round of data collection is: 28 sub-districts * 15 mauza * 25 hh = 10,500 households.

 

Urban slums

Households are selected from NGO working areas in the urban slums of six cities: Barisal (Wards 2, 6, 24), Chittagong (Wards 2, 11, 18, 28, 39, Wards 21 & 28 during Feb-May (rounds 90, 91), Wards 7 & 19 from June onwards rounds 92-95), Dhaka (Wards 1, 12, 16, 22, 27, 31, 34, 43, 48, 51, 58, 65), Khulna (Wards 3, 16, 27), Rajshahi (Wards 2, 19, 23) and Sylhet (Wards 8, 14, 27). Households were selected using a two-stage cluster sampling design. Slums were selected from each urban slum site using simple random sampling, and households were systematically sampled from each slum. Overall, 1500 households were selected from the six divisional cities: Barisal (150), Chittagong (300), Dhaka (600) Khulna (150), Rajshahi (150) and Sylhet (150).

Data collected

In each selected household, the weight and height/length of one mother and all her children below 5 years are measured. A precoded questionnaire is used to record the anthropometric measurements, together with other information on the health and nutrition of the mother and her children, household demography and socio-economic status, homestead food production and household food consumption.

The rural and urban slum questionnaires and codebooks provide further information on how the data that are shared on this CD-ROM were collected, including how the questions were asked and how the responses were coded.

  
Rural questionnaire Urban slum questionnaire
Rural codebook Urban slum codebook
Field team

The NSP works with a well-established local NGO in each rural sub-district and urban slum site. The NGO employs the field teams, which are responsible for selecting households according to the sampling design and for conducting the interviews. Each field team comprises two Data Collection Officers, one of whom is designated the Field Team Leader, and at least one of whom is a woman. The NGO also employs a Field Coordinator, who supervises data collection and provides administrative and logistic support to the field teams.

Field supervision and quality control

The NSP has a system of field supervision and quality control to ensure that good quality data are collected. Field Monitoring Officers supervise the field teams during each round of data collection, and provide support to the NGO partners in discussions with local officials. Quality Control Officers re-visit 5-10% of households without prior notice on the day following the data collection by the field teams and recollect data on selected indicators, including anthropometric measurements. Data collected by the Quality Control Officers are later compared with the data collected by the field teams to assess the accuracy of the data. Field teams who perform unsatisfactorily are either re-trained or dismissed, depending on any mitigating reasons and the seriousness of the situation.

Data entry and management

Each partner NGO employs at least one Data Entry Operator who enters the raw data from the questionnaires using a standard data entry package designed by HKI. The data files from all 24 rural sub-districts and six urban slum sites are merged at the HKI/NSP Data Management Unit in Dhaka. A Microsoft FoxProģ program is run to perform a series of checks for invalid data, which are then checked against the questionnaires before editing. The questionnaires are stored at HKI in Dhaka for at least 5 years.

Training

All field teams, Data Entry Operators, Field Monitoring Officers and Quality Control Officers are carefully selected and trained before they conduct their work. HKI provides two weeks of initial basic training to all these staff and refresher training for 2-3 days before each round of data collection. The refresher training allows the NGO staff to interact with HKI staff, share their experiences, and discuss problems encountered in the field. During these sessions any problems with data quality are shared and, where necessary, the sources of problems are identified and resolved. Special training is given when new questions are added or the questionnaire is modified. Through this interactive training process, HKI helps to develop the field staffís understanding of the surveillance system. Field teams have to demonstrate good performance during reliability tests that are performed by each field staff at least once per year.

Exploring the rural data

Guidelines for analyzing the data 

The data collected by the NSP in rural Bangladesh in 2005 are provided in two file types, an SPSS data file and a DBF data file. The SPSS data file needs to be used with SPSS for Windows software. The DBF data file can be read by most statistical packages, including EPI-INFO, which can be downloaded free of charge from the internet (www.cdc.gov/epiinfo/).  

Organization of the rural dataset 

The data file contains data collected on all children aged less than five years, their mothers and their households in rural Bangladesh by the NSP during six rounds of data collection between February 2005 and January 2006. For information on how the data were collected go to NSP data collection.

Each row in the data file provides all the data collected on a single child, together with the data collected on his/her mother and his/her household.  Each child is therefore a single case in the data file. The cases are sorted by round of data collection [ROUND], division [DIVISION], upazila [UPAZILA], mauza [MAUZA], household number [HHNO] and the identification number of each child [CID]. Each child is identified by a unique set of values for these six variables.

Each column in the data file provides all the data collected on a single variable. Most of the variables in the data file represent a single question in the questionnaire. For example, the variable [SDW] represents all data collected on the question ĎWhere does your household get drinking water?í Some variables have been computed from other variables. For example, the variable for child age [CAGE] was determined by finding the difference in months between a childís date of birth and the date of visit to the household.

See the rural codebook for information on the variables, including the variable names, variable labels, categories, missing values and notes on how the data were collected.

Calculating national rural statistics 

The NSP sampling design (see NSP data collection) provides statistics that are representative at the divisional and national level for rural Bangladesh.  

A weighting factor is applied to the data to produce national rural statistics for all children aged less than five years, mothers or households. This weighting factor is needed because the NSP samples the same number of households from each division in Bangladesh but each division has a different number of rural households. The rural dataset contains the variable [DWEIGHT] which is used to calculate national rural statistics. The weighting factor was calculated using data on the number of rural dwelling households by division taken from the 1991 population census (see Table 1). A more recent population census was conducted in 2001 but this data has not yet been published. Some statistical programs, including SPSS, have an option to weight data during statistical analysis. If this option is not available, the weighted statistics can be calculated manually using the values provided in Table 2. No weighting factors are needed to calculate divisional rural statistics.

 Table 1. The number of rural dwelling households by division in Bangladesh adjusted for undercounting.  

 

Number of rural dwelling households

Barisal

1,223,726

Chittagong

2,711,051

Chittagong Hill Tracts

  128,924

Dhaka

4,486,489

Khulna

1,910,033

Rajshahi

4,366,406

Sylhet

1,043,762

Total

 15,870,391 

 Source: 1991 population census, BBS.

 Table 2. Design weights for division by round of NSP data collection in 2005. 

 

Barisal

Chittagong

Chittagong Hill Tracts

Dhaka

Khulna

Rajshahi

Sylhet

Feb 2005

0.53970

1.19566

0.05686

1.97868

0.84238

1.92572

0.46064

Apr 2005

0.53970

1.19566

0.05686

1.97868

0.84238

1.92572

0.46064

Jun 2005

0.53975

1.19577

0.05686

1.97887

0.84246

1.92590

0.46038

Aug 2005

0.53975

1.19577

0.05686

1.97887

0.84246

1.92590

0.46038

Oct 2005

0.53975

1.19577

0.05686

1.97887

0.84246

1.92590

0.46038

Dec 2005

0.53975

1.19577

0.05686

1.97887

0.84246

1.92590

0.46038

Analysis of data on children

The NSP collects data on all children aged less than 5 years belonging to one mother in the selected households. If you wish to analyze data from only one child per mother/household, select cases that satisfy the condition [CID]=1. Note that this child is the motherís oldest child aged less than 60 months.

Indicators of a childís nutritional status

Key indicators of a childís nutritional status that can be determined using the NSP data provided on this CD-ROM are described below.

Malnutrition:   

The Z-scores of weight-for-age, height-for-age and weight-for-height have been calculated using NCHS growth references. The World Health Organization (WHO) recommends the following indicators of child malnutrition, based on these Z-scores:

 

Underweight (weight for age Z-score) 

   Underweight

[CWAZ]  <-2 SD

   Moderate underweight

[CWAZ]  -3 to <-2 SD

   Severe underweight

[CWAZ]  <-3 SD

 

 

Stunting (height for age z-score) 

   Stunting

[CHAZ]  <-2 SD

   Moderate stunting

[CHAZ]  -3 to <-2 SD

   Severe stunting

[CHAZ]  <-3 SD

 

 

Wasting (weight for height z-score) 

   Wasting

[CWHZ]  <-2 SD

   Moderate wasting

[CWHZ]  -3 to <-2 SD

   Severe wasting

[CWHZ]  <-3 SD

Source: WHO (1995). Physical Status: the Use and Interpretation of Anthropometry. WHO Technical Report Series 854. WHO, Geneva.

Analysis of data on mothers 

Mothers who have more than one child aged less than five years occur more than once in the dataset. When analyzing data collected from mothers it is important that each mother is selected only once using [CID]=1.

 Indicators of a motherís nutritional status

 Key indicators of a motherís nutritional status that can be determined using the NSP data provided on this CD-ROM are described below. For all of these indicators, it is important to consider the pregnancy status of the mothers. Non-pregnant mothers can be selected for analysis using [MPREG]=0 and pregnant mothers can be selected using [MPREG]>0.The variable [MBMI] identifies maternal nutritional status according to internationally agreed BMI-based categories. 

Chronic Energy Deficiency (CED):

The indicator for CED in non-pregnant women is body mass index (BMI), which is calculated by dividing a motherís weight in kilograms by the square of a motherís height in meters: [MWT]/[MHT/100]2. The different grades of motherís CED are defined as follows: 

Mild CED

BMI   17.0 - <18.5 kg/m2

Moderate CED

BMI   16.0 - <17.0 kg/m2

Severe CED

BMI <16.0 kg/m2 

Source: WHO (1995). Physical Status: the Use and Interpretation of Anthropometry. WHO Technical Report Series 854. WHO, Geneva.

Analysis of data on households

 A household occurs more than once in the dataset if the selected mother has more than one child aged less than five years. When analyzing data collected at the household level it is important that each household is selected only once using [CID]=1.

Guidelines for analyzing the data 

The data collected by the NSP in urban slums in Bangladesh in 2005 are provided in two file types, an  SPSS data file and a DBF data file. The SPSS data file needs to be used with SPSS for Windows software. The DBF data file can be read by most statistical packages, including EPI-INFO, which can be downloaded free of charge from the internet (www.cdc.gov/epiinfo/).  

Organization of the urban slum dataset

 The data file contains data collected on all children aged less than 5 years, their mothers and their households in the urban slum sites in Barisal, Dhaka, Chittagong, Khulna, Rajshahi and Sylhet by the NSP during six rounds of data collection between February 2005 and January 2006. For information on how the data were collected go to NSP data collection.  

Each row in the data file provides all the data collected on a single child, together with the data collected on his/her mother and his/her household.  Each child is therefore a single case in the data file. The cases are sorted by round of data collection [ROUND], urban slum site [CITY], urban slum [SLUM], household number [HHNO] and the identification number of each child [CID]. Each child is identified by a unique set of values for these five variables. 

Each column in the data file provides all the data collected on a single variable. Most of the variables in the data file represent a single question in the questionnaire. For example, the variable [SDW] represents all data collected on the question ĎWhere does your household get drinking water?í Some variables have been computed from other variables. For example, the variable for child age [CAGE] was determined by finding the difference in months between a childís date of birth and the date of visit to the household.  

See the urban slum codebook for information on the variables, including the variable names, variable labels, categories, missing values and notes on how the data were collected.

Calculating statistics on the urban slums

The six urban slum sites in the NSP urban sample are not randomly selected from all urban slums in Bangladesh (see NSP data collection for the sampling design) and so the data are not nationally representative of all urban slums in Bangladesh. As there are considerable differences in living conditions, health and nutrition between urban slums in Bangladesh, the data collected from each urban slum site should be analyzed separately and not aggregated with the data from the other urban slum sites.

Analysis of data on children 

The NSP collects data on all children aged less than five years belonging to one mother in the selected households. If you wish to analyze data from only one child per mother/household, select cases that satisfy the condition [CID]=1. Note that this child is the motherís oldest child aged less than 60 months. 

Indicators of a childís nutritional status 

Key indicators of a childís nutritional status that can be determined using the NSP data provided on this CD-ROM are described below. 

Malnutrition:      

The Z-scores of weight-for-age, height-for-age and weight-for-height have been calculated using NCHS growth references. The World Health Organization (WHO) recommends the following indicators of child malnutrition, based on these Z-scores:

 

Underweight (weight for age Z-score) 

   Underweight

[CWAZ]  <-2 SD

   Moderate underweight

[CWAZ]  -3 to <-2 SD

   Severe underweight

[CWAZ]  <-3 SD

 

 

Stunting (height for age z-score) 

   Stunting

[CHAZ]  <-2 SD

   Moderate stunting

[CHAZ]  -3 to <-2 SD

   Severe stunting

[CHAZ]  <-3 SD

 

 

Wasting (weight for height z-score) 

   Wasting

[CWHZ]  <-2 SD

   Moderate wasting

[CWHZ]  -3 to <-2 SD

   Severe wasting

[CWHZ]  <-3 SD

  Source: WHO (1995). Physical Status: the Use and Interpretation of Anthropometry. WHO Technical Report Series 854. WHO, Geneva.

Analysis of data on mothers 

Mothers who have more than one child aged less than 5 years occur more than once in the dataset. When analyzing data collected from mothers it is important that each mother is selected only once using [CID]=1.  

Indicators of a motherís nutritional status 

Key indicators of a motherís nutritional status that can be determined using the NSP data provided on this CD-ROM are described below. For all of these indicators, it is important to consider the pregnancy status of the mothers. Non-pregnant mothers can be selected for analysis using [MPREG]=0 and pregnant mothers can be selected using [MPREG]>0.The variable [MBMI] identifies maternal nutritional status according to internationally agreed BMI-based categories. 

Chronic Energy Deficiency (CED):

The indicator for CED in non-pregnant women is body mass index (BMI), which is calculated by dividing a motherís weight in kilograms by the square of a motherís height in meters: [MWT]/[MHT/100]2. The different grades of motherís CED are defined as follows:

Mild CED

BMI   17.0 - <18.5 kg/m2

Moderate CED

BMI   16.0 - <17.0 kg/m2

Severe CED

BMI <16.0 kg/m2

 

Source: WHO (1995). Physical Status: the Use and Interpretation of Anthropometry. WHO Technical Report Series 854. WHO, Geneva.

Analysis of data on households 

A household occurs more than once in the dataset if the selected mother has more than one child aged less than five years. When analyzing data collected at the household level it is important that each household is selected only once using [CID]=1.

 

 

 

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