Malaria Indicator Survey 2010 - Nigeria

Abstract
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The 2010 Nigeria Malaria Indicator Survey (2010 NMIS) was implemented by the National Population Commission (NPC) and the National Malaria Control Programme (NMCP). ICF International provided technical assistance through the MEASURE DHS programme, a project funded by the United States Agency for International Development (USAID), which provides support and technical assistance in the implementation of population and health surveys in countries worldwide. It was carried out from October to December 2010 on a nationally representative sample of more than 6,000 households. All women age 15-49 in the selected households were eligible for individual interviews. During the interviews, they were asked questions about malaria prevention during pregnancy and the treatment of fever among their children. In addition, the survey included testing for anaemia and malaria among children age 6-59 months using finger (or heel) prick blood samples. Test results were available immediately and were provided to the children’s parents or guardians. Thick blood smears and thin blood films were also made in the field and transported to the Department of Medical Microbiology and Parasitology at the College of Medicine, University of Lagos. Microscopy was performed to determine the presence of malaria parasites and to identify the parasite species. Slide validation was carried out by the University of Calabar Teaching Hospital in Calabar.

The 2009-2013 National Strategic Plan for Malaria Control in Nigeria aims to massively scale up malaria control interventions in parts of the country. The 2010 Nigeria Malaria Indicator Survey (NMIS) was, therefore, designed to measure progress toward achieving the goals and targets of this strategic plan by providing data on key malaria indicators, including ownership and use of bed nets, diagnosis and prompt treatment of malaria using artemisinin-based therapy (ACT), indoor residual spraying, and behaviour change communication.

The following are the specific objectives of the 2010 NMIS:
- To measure the extent of ownership and use of mosquito bed nets
- To assess the coverage of intermittent and preventive treatment programmes for pregnant women
- To identify practices used to treat malaria among children under age 5 and the use of specific antimalarial medications
- To measure the prevalence of malaria and anaemia among children age 6-59 months
- To determine the species of plasmodium parasite most prevalent in Nigeria
- To assess knowledge, attitudes, and practices regarding malaria in the general population

Geographic coverage
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National

Analysis unit
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- Household,
- Individual.

Universe
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The survey covered all de jure household members (usual residents), all women aged between 15-49 years, and all children age 6-59 months living in the household.

Kind of data
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Sample survey data [ssd]

Sampling procedure
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The 2010 Nigeria Malaria Indicator Survey (NMIS) called for a nationally representative sample of about 6,000 households. The survey is designed to provide information on key malaria-related indicators including mosquito net ownership and use, coverage of preventive treatment for pregnant women, treatment of childhood fever, and the prevalence of anaemia and malaria among children age 6-59 months. The sample for the 2010 NMIS was designed to provide most of these indicators for the country as a whole, for urban and rural areas separately, and for each of the six zones formed by grouping the 36 states and the Federal Capital Territory (FCT). The zones are as follows:
1. North Central: Benue, FCT-Abuja, Kogi, Kwara, Nasarawa, Niger, and Plateau
2. North East: Adamawa, Bauchi, Borno, Gombe, Taraba, and Yobe
3. North West: Jigawa, Kaduna, Kano, Katsina, Kebbi, Sokoto, and Zamfara
4. South East: Abia, Anambra, Ebonyi, Enugu, and Imo
5. South South: Akwa Ibom, Bayelsa, Cross River, Delta, Edo, and Rivers
6. South West: Ekiti, Lagos, Ogun, Ondo, Osun, and Oyo

SAMPLING FRAME
The sampling frame used for the 2010 NMIS was the Population and Housing Census of the Federal Republic of Nigeria, which was conducted in 2006 by the National Population Commission (NPC). Administratively, Nigeria is divided into states. Each state is subdivided into local government areas (LGAs), and each LGA is divided into localities. In addition to these administrative units, during the 2006 Population Census, each locality was subdivided into convenient areas called census enumeration areas (EAs). The primary sampling unit (PSU), referred to as a cluster for the 2010 NMIS, is defined on the basis of EAs from the 2006 EA census frame.

Although the 2006 Population Census did not provide the number of households and population for each EA, population estimates were published for more than 800 LGA units. A combination of information from cartographic material demarcating each EA and the LGA population estimates from the census were used to identify the list of EAs, estimate the number of households, and distinguish EAs as urban or rual for the survey sample frame.

SAMPLE ALLOCATION
The 2010 NMIS sample was selected using a stratified, two-stage cluster design consisting of 240 clusters, 83 in the urban areas and 157 in the rural areas. (The final sample included 239 clusters because access to one cluster was prevented by inter-communal disturbances.) A sample of 6,240 households was selected for the survey, with a minimum target of 920 completed individual women's interviews per zone. Within each zone, the number of households was distributed proportionately among urban and rural areas. A fixed 'take' of 26 households per cluster was adopted for both urban and rural clusters.

SAMPLING PROCEDURE AND UPDATING OF THE SAMPLING FRAME
The 2010 NMIS sample is a stratified sample selected in two stages. The primary sampling units (PSUs) are the enumeration areas (EAs) from the 2006 census, and the secondary sampling units (SSUs) are the households. In the first stage of selection, the 240 EAs were selected with a probability proportional to the size of the EA, where size is the number of approximate households calculated within the sampling frame.

A complete listing of households and a mapping exercise for each cluster was carried out from August through September 2010. The lists of households resulting from this exercise served as the sampling frame for the selection of households in the second stage. In addition to listing the households, the NPC listing enumerators used global positioning system (GPS) receivers to record the coordinates of the 2010 NMIS sample clusters.

In the second stage of the selection process, 26 households were selected in each cluster by equal probability systematic sampling. All women age 15-49 who were either permanent residents of the households in the 2010 NMIS sample or visitors present in the households on the night before the survey were eligible to be interviewed. In addition, all children age 6-59 months were eligible to be tested for malaria and anaemia.

The sampling procedures are fully described in Appendix A of "Nigeria Malaria Indicator Survey 2010 - Final Report" pp.69-71.

Mode of data collection
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Face-to-face [f2f]

Research instrument
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Two questionnaires were used in the NMIS: a Household Questionnaire and a Woman’s Questionnaire, which was administered to all women age 15-49 in the selected households. Both instruments were based on the standard Malaria Indicator Survey Questionnaires developed by the Roll Back Malaria and DHS programmes. These questionnaires were adapted to reflect the population and health issues relevant to Nigeria during a series of meetings convened with various stakeholders from the NMCP and other government ministries and agencies, nongovernmental organisations, and international donors. The questionnaires were translated into three major Nigerian languages: Hausa, Igbo, and Yoruba.

The Household Questionnaire was used to list all the usual members and visitors in the selected households. Some basic information was collected on the characteristics of each person listed, including age, sex, and relationship to the head of the household. The main purpose of the Household Questionnaire was to identify women who were eligible for the individual interview and children age 6-59 months who were eligible for anaemia and malaria testing. The Household Questionnaire also collected information on characteristics of the household’s dwelling unit, such as the source of water; type of toilet facilities; materials used for the floor, roof, and walls of the house; ownership of various durable goods; and ownership and use of mosquito nets. In addition, the questionnaire was used to record the results of the anaemia and malaria testing as well as the signatures of the interviewer and the respondent who gave consent. Children’s temperatures were also recorded.

The Woman’s Questionnaire was used to collect information from all women age 15-49. These women were asked questions on the following main topics:
- Background characteristics (such as age, residence, education, media exposure, and literacy)
- Birth history and childhood mortality
- Antenatal care and malaria prevention for most recent birth and pregnancy
- Malaria prevention and treatment
- Knowledge about malaria (symptoms, causes, prevention, and drugs used in treatment)

Cleaning operations
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The processing of data for the 2010 NMIS ran concurrently with data collection. Completed questionnaires were retrieved by the zonal coordinators or the trainers and delivered to NPC in standard envelopes, labelled with the sample ID, team number, and state name. The shipment also contained a written summary of any issues detected during the data collection process.

The questionnaire administrators logged the receipt of the questionnaires, acknowledged the specified issues, and acted upon them if required. The data editors performed an initial check on the questionnaires, as well as coding of open-ended questions (with assistance from the data entry operators). The questionnaires were then assigned to the data entry operators. The data entry operators entered the data into the system, with the support of the data editors who handled erroneous or unclear data.

Data entry personnel were recruited from staff experienced in data entry activities from previous studies. The data entry team consisted of a supervisor, a data entry coordinator, and the data entry operators. Supervisors monitored the entire data entry and editing process, controlled the incoming questionnaires, assigned batches of questionnaires to the data entry operators, and managed the work progress. They were available at all times to ensure that proper procedures were followed and to help editors resolve inconsistencies. Data entry coordinators assisted with coordinating and overseeing the data entry process, assigning the work, tracking progress, and ensuring the quality and timeliness of the data entry process. Approximately 15 clerks were recruited and trained as data entry operators to enter all completed questionnaires and to perform the secondary entry for data verification. Two office editors and one secondary editor worked with the data entry operators to review information flagged as ‘erroneous’ or ‘dubious’ in the data entry process and to provide follow up and resolution for those anomalies.

Data entry and editing were accomplished using CSPro software. The processing of data was initiated in October 2010 and completed in February 2011.

Response rate
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A total of 6,197 households were selected, and of these 5,986 were occupied. Of the occupied households, 5,895 had occupants who were successfully interviewed, yielding a household response rate of 99 percent. There are no significant differences in the household response rates between rural and urban areas.

In the interviewed households, a total of 6,527 women were identified as eligible for the individual interview, and 97 percent of them were successfully interviewed.

Sampling error estimates
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Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the 2010 NMIS 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 2010 NMIS 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 2010 NMIS is the ISSA Sampling Error Module. This module used the Taylor linearisation 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.

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 if a 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 2010 NMIS are calculated for selected variables considered to be of primary interest for the woman’s survey. The results are presented in this appendix for the country as a whole, for urban and rural areas, and for each of the 6 zones. For each variable, the type of statistic (mean, proportion, or rate) and the base population are given in Table B.1. Tables B.2 to B.10 present the value of the statistic (R), its standard error (SE), the number of unweighted (N-UNWE) and weighted (NWEIG) cases, the design effect (DEFT), the relative standard error (SE/R), and the 95 percent confidence limits (R±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).

The confidence interval (e.g., as calculated for the proportion of all women 15-49 with secondary education or higher) can be interpreted as follows: the overall proportion from the national sample is 0.405 and its standard error is 0.019. Therefore, to obtain the 95 percent confidence limits, one adds and subtracts twice the standard error to the sample estimate, i.e., 0.405 ± 2 × 0.019. There is a high probability (95 percent) that the true proportion of women with secondary education or higher for all women aged 15 to 49 is between 0.366 and 0.443

Sampling errors are analysed for the national woman sample and a group of estimated proportions. The relative standard errors (SE/R) for the selected proportions range between almost 2 percent and 10 percent. But in general, the relative standard error for most estimates for the country as a whole is small.

There are differentials in the relative standard error for the estimates of sub-populations. For example, for the variable secondary education or higher for women aged 40-49, the relative standard errors, as a percent of the estimated mean for the whole country, for the urban areas, and for the rural areas are 4.8 percent, 4.6 percent, and 7.0 percent, respectively. For the total sample, the value of the design effect (DEFT), averaged over all selected variables, is 2.9326, which means that due to multi-stage clustering of the sample, the average standard error is increased by a factor of 2.9326 over that in an equivalent simple random sample.

The sampling errors are fully described in Appendix B of " Nigeria Malaria Indicator Survey 2010 - Final Report" pp.73-78.

Data appraisal
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A series of data quality tables are available to review the quality of the data and include the following:

- Household age distribution
- Age distribution of eligible and interviewed women

The results of each of these data quality tables are shown in Appendix C of "Nigeria Malaria Indicator Survey 2010 - Final Report" pp.79-80.

摘要
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2010年尼日利亚疟疾指标调查（2010年NMIS）由国家人口委员会（NPC）和国家疟疾控制计划（NMCP）实施。国际咨询公司（ICF）通过MEASURE DHS项目提供技术援助，该项目由美国国际开发署（USAID）资助，旨在为全球各国实施人口与健康调查提供支持和专业技术援助。该调查于2010年10月至12月在全国范围内对超过6,000个家庭进行了代表性抽样调查。在所选家庭中，所有15至49岁的女性均有资格接受个别访谈。在访谈过程中，她们被问及孕期的疟疾预防措施以及儿童发热的治疗情况。此外，调查还包括对6至59个月大的儿童进行贫血和疟疾的检测，使用指尖（或脚跟）血液样本进行检测。检测结果立即提供给孩子父母或监护人。厚血涂片和薄血膜在现场制作，并运送至拉各斯大学医学院医学微生物学和寄生虫学系。通过显微镜检查确定疟原虫的存在并识别寄生虫种类。卡诺教学医院在卡诺进行了样本验证。

2009-2013年尼日利亚疟疾控制国家战略计划旨在大幅扩大全国疟疾控制干预措施。因此，2010年尼日利亚疟疾指标调查（NMIS）旨在通过提供关键疟疾指标数据，包括蚊帐拥有和使用率、基于青蒿素的疗法（ACT）诊断和治疗疟疾、室内残留喷洒和行为改变沟通，来衡量实现该战略计划目标和进展。

以下是2010年NMIS的具体目标：
- 衡量蚊帐拥有和使用程度
- 评估孕妇间歇性和预防性治疗计划的覆盖率
- 识别5岁以下儿童治疗疟疾的实践和特定抗疟疾药物的使用
- 衡量6至59个月大儿童疟疾和贫血的患病率
- 确定在尼日利亚最普遍的疟原虫种类
- 评估一般人群对疟疾的知识、态度和实践

地理覆盖范围
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全国

分析单元
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- 家庭,
- 个人。

总体
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调查涵盖了所有法定家庭成员（常住居民），所有15至49岁的女性，以及所有居住在家庭中的6至59个月大的儿童。

数据类型
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样本调查数据 [ssd]

抽样程序
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2010年尼日利亚疟疾指标调查（NMIS）要求对大约6,000个家庭进行全国代表性抽样。该调查旨在提供有关关键疟疾相关指标的信息，包括蚊帐拥有和使用率、孕妇预防性治疗的覆盖率、儿童发热的治疗，以及6至59个月大儿童贫血和疟疾的患病率。2010年NMIS的样本设计旨在为整个国家、城市和农村地区以及由36个州和联邦首都特区（FCT）组成的六个区域中的每一个提供这些指标的大部分数据。区域如下：
1. 北部中央：本图、阿布贾FCT、科吉、克瓦拉、纳萨拉瓦、尼日尔和 Plateau
2. 北部东北：阿达马瓦、包奇、博尔诺、戈梅、塔拉巴和约贝
3. 北部西北：吉加瓦、卡杜纳、卡诺、卡齐纳、凯贝比、索科托和赞法拉
4. 南部东部：阿比亚、安ambra、伊博、恩古和伊莫
5. 南部南部：阿卡伊布姆、贝努埃、克罗斯河、德尔塔、埃多和河流
6. 南部西部：埃kiti、拉各斯、奥贡、奥ndo、奥孙和奥约

抽样框

用于2010年NMIS的抽样框是2006年由国家人口委员会（NPC）进行的联邦共和国人口和住房普查。从行政上讲，尼日利亚分为州。每个州被划分为地方政府（LGA），每个LGA被划分为地区。除了这些行政单位外，在2006年人口普查期间，每个地区还被划分为方便的区域，称为普查枚举区域（EA）。一级抽样单位（PSU），在2010年NMIS中称为集群，是根据2006年EA普查框架中的EA定义的。

尽管2006年人口普查没有提供每个EA的家庭和人口数量，但已发布了超过800个LGA单位的估计人口。结合来自标记每个EA的地图材料和李嘉图人口估计，用于确定EA列表、估计家庭数量以及将EA区分城市或农村的抽样框。

抽样分配

2010年NMIS样本采用分层、两阶段集群设计，包括240个集群，其中城市地区83个，农村地区157个。（由于社区冲突，最终样本中包含239个集群。）为调查选择了6,240个家庭样本，每个区域的目标至少完成920次女性个别访谈。在每个区域内部，家庭数量按比例分配到城市和农村地区。每个集群采用固定的26户家庭‘采取’。

抽样程序和抽样框的更新

2010年NMIS样本是分层样本，分两阶段选择。一级抽样单位（PSU）是2006年普查的枚举区域（EA），二级抽样单位（SSU）是家庭。在第一阶段的选择中，根据EA的大小（在抽样框内计算的大致家庭数量）以概率成比例地选择了240个EA。

在2006年人口普查期间，从8月到9月，对每个集群进行了完整的家庭清单和绘图作业。此作业产生的家庭清单作为第二阶段选择家庭的家庭抽样框。除了清单家庭外，NPC清单编制员还使用全球定位系统（GPS）接收器记录2010年NMIS样本集群的坐标。

在选择的第二阶段，通过等概率系统抽样在每个集群中选择了26个家庭。在2010年NMIS样本中，所有15至49岁且为家庭永久居民或调查前夜在家庭中出现的访客均有资格接受访谈。此外，所有6至59个月大的儿童均有资格接受疟疾和贫血检测。

抽样程序在“尼日利亚疟疾指标调查2010年 - 最终报告”附录A的第69-71页中进行了全面描述。

数据收集方式
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面对面 [f2f]

研究工具
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在NMIS中使用了两种问卷：家庭问卷和女性问卷，后者用于对所选家庭中所有15至49岁的女性进行管理。这两种工具都是基于由Roll Back Malaria和DHS项目开发的标准化疟疾指标调查问卷。这些问卷在一系列与NMCP和其他政府部

门和机构、非政府组织以及国际捐助者利益相关者举行的会议上进行了调整，以反映与尼日利亚相关的人口和健康问题。问卷被翻译成三种主要尼日利亚语言：豪萨语、伊博语和约鲁巴语。

家庭问卷用于列出所选家庭中的所有常住成员和访客。收集了有关列出的每个人的基本信息的某些信息，包括年龄、性别和与户主的关系。家庭问卷的主要目的是确定有资格进行个别访谈的女性以及有资格接受贫血和疟疾检测的6至59个月大的儿童。家庭问卷还收集有关家庭居住单位特征的信息，例如水源；厕所设施类型；房屋地板、屋顶和墙壁的材料；耐用商品的拥有权；以及蚊帐的拥有和使用情况。此外，问卷还用于记录贫血和疟疾检测结果以及访谈者和受访者的签名。还记录了儿童的体温。

女性问卷用于收集所有15至49岁女性的信息。这些女性被问及以下主要主题：
- 背景特征（例如年龄、居住地、教育、媒体接触和读写能力）
- 出生史和儿童死亡率
- 最近一次分娩和怀孕的产前护理和疟疾预防
- 疟疾预防和治疗
- 对疟疾的了解（症状、原因、预防措施和治疗中使用的药物）

数据清理操作
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2010年NMIS数据的处理与数据收集同时进行。完成的问卷由区域协调员或培训师收回，并以标准信封发送至NPC，信封上标有样本ID、团队编号和州名。 shipment 还包含一份关于数据收集过程中发现的任何问题的书面总结。

问卷管理员记录了问卷的接收情况，确认了指定的问题，并在需要时采取行动。数据编辑员对问卷进行了初步检查，以及对开放式问题的编码（在数据录入员协助下）。然后将问卷分配给数据录入员。数据录入员将数据输入系统，数据编辑员处理错误或不清晰的数据。

数据录入人员是从以前研究中具有数据录入活动经验的工作人员中招募的。数据录入团队由一名监督员、一名数据录入协调员和数据录入员组成。监督员监控整个数据录入和编辑过程，控制收到的问卷，将问卷批分配给数据录入员，并管理工作进度。他们随时可用，以确保遵循适当的程序，并帮助编辑解决不一致之处。数据录入协调员协助协调和监督数据录入过程，分配工作，跟踪进度，并确保数据录入过程的质量和及时性。大约招募了15名职员，并培训为数据录入员，以输入所有完成的问卷并执行数据验证的二级录入。两名办公室编辑和一名二级编辑与数据录入员合作，审查在数据录入过程中标记为“错误”或“可疑”的信息，并为这些异常提供跟进和解决。

数据录入和编辑使用CSPro软件完成。数据处理始于2010年10月，并于2011年2月完成。

响应率
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总共选择了6,197个家庭，其中5,986个被占用。在这些被占用的家庭中，5,895个家庭有居民接受了成功访谈，从而产生了99%的家庭响应率。农村和城市地区的家庭响应率之间没有显著差异。

在访谈的家庭中，总共确定了6,527名有资格进行个别访谈的女性，其中97%的女性接受了成功访谈。

抽样误差估计
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另一方面，抽样误差可以通过统计方法进行评估。2010年NMIS中选定的受访者样本只是从同一人口中，使用相同的设计和预期规模可以选出的许多样本之一。这些样本中的每一个都会产生与实际选定的样本结果略有不同的结果。抽样误差是衡量所有可能样本之间差异的指标。尽管差异的程度无法确切知道，但可以从调查结果中估计出来。

抽样误差通常以特定统计量（平均值、百分比等）的标准误差来衡量，这是方差的平方根。标准误差可用于计算置信区间，在这个区间内，可以合理地假设总体中真实值的范围。例如，对于从样本调查中计算的任何给定的统计量，该统计量的值将在所有可能的样本中占相同大小和设计的95%的样本中加减两倍标准误差的范围内。

如果受访者样本被选为简单随机样本，则可以使用简单的公式来计算抽样误差。但是，2010年NMIS样本是分层多阶段设计的产物，因此有必要使用更复杂的公式。用于计算2010年NMIS抽样误差的计算机软件是ISSA抽样误差模块。该模块使用Taylor线性化方法对调查估计进行方差估计，这些估计是平均值或比例。对于更复杂的统计量，如生育率和死亡率，使用Jackknife重复复制方法进行方差估计。

除了标准误差外，ISSA还为每个估计计算设计效应（DEFT），该效应定义为使用给定样本设计计算的标准误差与使用简单随机样本将产生的标准误差之比。DEFT值为1.0表示样本设计与简单随机样本一样有效，而值大于1.0表示由于使用更复杂且统计上效率较低的

设计而增加的抽样误差。ISSA还计算估计的相对误差和置信限。

2010年NMIS的抽样误差根据女性调查中被认为对主要变量感兴趣的选定变量进行计算。结果按国家总体、城市和农村地区以及每个6个区域进行展示。对于每个变量，给出统计量类型（平均值、比例或比率）和基

本人口在表B.1中。表B.2至B.10呈现了统计量的值（R），其标准误差（SE），未加权（N-UNWE）和加权（NWEIG）案例数量，设计效应（DEFT），相对标准误差（SE/R），以及每个变量的95