Data and Methods

In this page we explain the process followed by Development Gateway in the development of the TCDI Nigeria website, as well as a description of the data sources and analysis methods used in each of the website’s themes.

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Methodology

View the methodologies for the respective themes

Methodology Overview

The TCDI Nigeria website was developed by Development Gateway. The website is intended to respond to the needs of government, civil society and academic stakeholders by providing access to demand-driven, high-quality data on national tobacco prevalence, products, and policies. The design, functionality and content for the website are led by the Nigerian tobacco control community’s needs. This document outlines our overall website development methodology.

1. Identifying Stakeholder Needs

From June to July 2020, the TCDI Nigeria team conducted interviews with 20 organizations which included representatives from the government, civil-society organizations and academia. As a result of the COVID-19 pandemic, the interviews were conducted virtually. The interviews aimed to explore how they make decisions, the data production and use for these decisions, potential data gaps, and data opportunities.  

2. Reviewing Stakeholder Feedback and Prioritising Needs

The stakeholder feedback was documented during the interviews and later analysed to identify cross-cutting data gaps and the stakeholders’ preferred online tool formats for receiving information. This process identified 19 data gaps which were later narrowed down to six during a stakeholder co-design workshop, based  on the frequency and urgency with which each was mentioned by the stakeholders. The process also identified 7 data format guidelines:

Priority Data Gaps

  1. Use and prevalence of shisha, particularly by young people
  2. Illicit Trade
  3. Tobacco use prevalence
  4. Taxation
  5. Tobacco Harm
  6. Tobacco Industry Interference

Preferred online tool format

  1. Interactive website
  2. Factsheets / One pagers
  3. Graphics e.g. charts/interactive graphs
  4. Data repository/ online library
  5. Infographics
  6. Maps
  7. Tables
  8. Stories

The stakeholders also identified the need for  training, data access/availability, and time for analysis for them to be able to use the data effectively.  

3. Research and Analysis

The TCDI team conducted research and data analysis for each theme, including secondary analysis  of already available and reliable datasets (e.g. data collected by academic institutions, global foundations or governments) and reviews of existing literature (e.g. peer-reviewed academic articles). Where required, the datasets were analysed using statistical software such as Stata and R.  Relevant statistics and graphs were produced, and explanatory text was written.

4. Website Design

Using the eight data tool format guidelines as a starting point, the TCDI team designed the visual elements and functionality of the website. This process included designing the visual elements (infographics, chart formats and colours) and the user functionality (menus, data exports and search functionality).

5. Expert Review

At least two Nigerian tobacco control subject matter experts were selected per theme to review the quality, context and reliability of the content. The University of Cape Town has also been involved in the review process. Their feedback was integrated into the text and the design of the website.

6. Periodic Updates

Periodically, the TCDI team will consult with experts, review newly available data, and update the website to reflect any changes, where necessary. Please fill out the Showcase Your Work form if you have newly available data or publications you would like to share.

TCDI Nigeria used the 2018 Nigeria Demographic and Health Survey (NDHS) data to calculate tobacco use prevalence for different products and sub-groups of the population. To estimate the population size, we used UNDP Population estimates for 2018. The analysis was conducted using the statistical software, R. The DHS data is available for download here, and the R code here.

Nigeria DHS is a household survey that is done approximately every 5 years. The latest one was conducted in 2018 and it aimed to provide up-to-date estimates of basic demographic and health indicators. The information collected through the 2018 NDHS intended to assist policymakers and programme managers in evaluating and designing programmes and strategies for improving the health of the country’s population. The survey collected information on themes such as nutrition, HIV/AIDS and smoking, among others. Prevalence of tobacco smoking was determined by the answers of participants aged 15 years and older to the question: “Do you currently smoke tobacco every day, some days, or not at all?” Those who answered “every day/some days” were classified as current tobacco smokers, whilst those who answered “not at all” were regarded as current non-smoke.

The 2018 NDHS was nationally representative with over 42,000 households across the country’s six geopolitical zones and 36 states with a target group of women aged 15-49 and men aged 15-59. A total of 41,668 households were selected for the sample, of which 40,666 were occupied. Of the occupied households, 40,427 were successfully interviewed putting the overall response rate in 2018 at 99%. The data collected by NDHS are weighted so that proportions are those of the full population, but in order to calculate the population totals, the data needs to be reweighted. To do this, population estimates are required to calculate the number of smokers from the prevalence rates. DHS, unlike some other surveys, weights the data so that the weighted total is the same as the unweighted sample size. The weights can be rescaled using population estimates.

In total, 55,132 adults (15+ years) provided answers to the tobacco smoking question (excluding those that refused to answer or said they did not know). The tobacco smoking prevalence rates are calculated by dividing the number of tobacco smokers in the sample by the total sample and multiplying by the weights. 

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smoking prevalence equation

Individuals who did not answer the smoking questions were excluded from the analysis. We tested whether smoking prevalence rates were statistically significantly different from one another by comparing confidence intervals1 for each estimate. The TCDI team calculated prevalence rates for the following groups: 

  • Nine age categories were identified for the smoking prevalence by age analysis: The age categories were (15-19, 20-24 ,25-29, 30-34, 35-39,40-44, 45-49, 50-54, 55-59). In our analysis, we dropped ages < 15 and > 59 (men) and > 49 (women).
  • For the education analysis, respondents were categorised by the highest level of education attained, unless they were in an educational institution at the time of the survey. The educational categories include: no education; primary education; secondary education and higher education. 
  • For location, households were categorised into urban and rural. “Nigeria adopts a threshold population of 20,000 people as a criterion for defining an urban centre. In addition to this, all states and local government area headquarters have historically legally or administratively regarded as urban centres.”
  • For zones, the households were categorized into six zones (North Central North East, North West, South East, South South and South West)

The taxation page discusses and provides information on tobacco tax policies in Nigeria, effects of tax increase on tobacco products as well as discrediting tobacco industry arguments against tax increases. 

In addition to drawing on secondary sources, data analysis was conducted by the TCDI team to predict how increases in tax will affect consumption, government revenue, and mortality using a Tobacco Excise Tax Simulation Model (TETSiM) developed by the Research Unit on the Economics of Excisable Products (REEP). TETSiM is a “tool to quantify the likely impact of a change in the excise tax structure and/or the level of the excise tax on a number of variables, including the price of cigarettes, cigarette consumption and excise tax revenue.”

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License

The content in this website is licensed under the Creative Commons Attribution-NonCommercial 4.0 International license. Users of this website can copy and redistribute the material in any medium or format, as well as remix, transform, and build upon the data. When reusing the data, users must:

1.

Credit Tobacco Control Data Initiative as the source of data and indicate if changes are made to the data. 

2.

If content is shared, it needs to be done using the same licence or similar license. Users cannot share the data with more restrictive rights to use than under the original website license. 

3.

Users can use the data as they see fit, but cannot use the material for commercial purposes.

See the full license terms here. 

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Disclaimer

The information displayed on this website is obtained from multiple sources and has undergone a rigorous verification process. Nevertheless, the accuracy and validity of data and information cannot be guaranteed. The website should therefore be used for guidance only. The TCDI team, and the authors whom we reference, cannot be held responsible for how the information is used.

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Contact details 

For any queries on the TCDI methodological approach and data sources, kindly contact the TCDI Data Manager.

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References

1. When estimating statistics from surveys and samples, it is possible that the calculated average values are not exactly the averages of the whole population. The confidence interval of a statistic is the range of values around that statistic that has a defined level of probability of containing the true value of the statistic for the entire population. We usually use a 95% confidence interval. This means that we are 95% certain the interval contains the true value. When comparing two statistics, for example the prevalence of smoking in two different population groups, we can only conclude that the prevalence is significantly different between the groups if their confidence intervals do not overlap. If they overlap, the true population value may be the same for each group.

2. Ofem, B. (2012). A Review of the Criteria for Defining Urban Areas in Nigeria. Journal of Human Ecology. Volume 37 Issue 3. A Review of the Criteria for Defining Urban Areas in Nigeria. https://doi.org/10.1080/09709274.2012.11906461

3. Van der Zee, K. and Van Walbeek, C. (2020). The TETSiM Model, REEP Back to Basics Policy Brief: B2B#8. University of Cape Town. https://untobaccocontrol.org/kh/taxation/wp-content/uploads/sites/3/2020/05/KH_1pager-8_The-TETSiM-Model.pdf