class: center, middle, inverse, title-slide .title[ # <code>Sources of Demographic Data</code> ] .subtitle[ ## Lecture 3 (Demography) ] .author[ ### Dr. Zulfiqar Ali (Assistant Professor) ] .institute[ ### College of Statistcal Sciences, University of the Punjab, Lahore ] .date[ ### 15 June 2023 ] --- #Introduction - Demographic data are important in providing factual basis for decisions on matters of public policy and action concerning social and economic affairs. - These data can be processed to indicate present and future requirements of the population in terms of the types and extent of social needs of the society such as health, education and employment. --- # Sources of Demographic Data ## The major sources of demographic data include: - Census, Conducted by national statistical agencies - Registration of vital events (Administrative Records) - Sample surveys - Ad-hoc Demographic studies - Big Data Sources --- ## Census ### Definition - Census is defined as an enumeration or complete population count at a point in time within a specified geographical area. - A census provides more reliable and accurate data if properly enumerated. --- ## Census ### History - The conducting of censuses has a long history, but modern censuses were first held in the 17th century. - By the end of eighteenth and beginning of the nineteenth century many countries had held their first censuses. - Some countries including Ethiopia have only recently held their first censuses. --- ## Administrative Records - Data collected by government agencies for administrative purposes - Examples: Tax records, social security records, birth and death records - Provide accurate and up-to-date information - Limited to certain variables and populations - It is a regular and continuous registration of vital events. Civil registration system, which records births, deaths, marriages etc. (vital statistics), enables rates of population growth to be calculated; but are much less adequate than national censuses. - In developing countries where illiteracy rates are high and communications are poor, the problems of recording births and deaths are immense not only in rural populations but also in urban areas. - However, efforts are being made to improve the collection of these data in many countries. --- ## Sample Survey - A sample survey is another source of demographic data carried out in a scientifically selected area which covers only a section or portion (sample) of the population under consideration. - To conduct sample survey, there are a number of probability sample designs that are available. Only four designs that are commonly used are described below. - In many surveys more than one sampling techniques may be used --- ## Most poupular sampling design ### Simple Random Sampling - In simple random sampling, individuals or households or items or events are randomly selected from the whole population to be sampled, often using random numbers. - Each individual item has an equal chance of being selected and given equal value. This is the simplest of probability sampling techniques. --- ## Most poupular sampling design ### Systematic Sampling - For the systematic sampling, an inventory (list) of individuals or households or items or events is compiled or is available to constitute the sampling frame. - Then, say, every fifth or tenth individual or household on the list is selected for the sample. - This is not strictly a random sample but is usually a reasonable practice, as long as there is no bias in the structure or order of the listing or some periodicity. --- ## Most poupular sampling design ### Multistage Sampling - The multistage sampling usually involves the random selection of a higher order unit such as a region. - From this, a second stage sampling may involve the random selection of households in that region. - In a third stage, individuals may be randomly selected from the households selected. --- ## Most poupular sampling design ### Stratified Sampling - The stratified sampling technique ensures sufficient representation in the sample of different groups in the population, the sample may be made up of strata according to the characteristics of different groups in the population. - This may result in a lower cost and more representative sample. - The strata size may be in proportion to its proportion in the population, otherwise relative weights need to be given to each stratum in relation to its proportion in the population. --- ## Most poupular sampling design ### Cluster Sampling - Cluster sampling may be used when the population to be sampled is bunched and each bunch or group is close to being representative of the population or having similar characteristics. - The clusters are randomly selected and every individual, or household, or item or event in the selected clusters may be included in the sample. - In order to ensure representative findings, it is important that either the clusters are all of the same size or weights are assigned to overcome the difference in size of the different clusters. --- #Demographic Information - Surveys can be concerned with a variety of demographic information such as fertility, health and disability status, labour force participation, training and occupation, income levels, wealth and poverty, nutrition and exercise, time use and household expenditure. - They may be ad hoc in nature or be undertaken periodically and allow for the assessment of change and trends over time. - They may be concerned with the whole population or defined groups within it. - As is the case with a full census, the major trade-off in a sample survey is between precision, cost and time --- ## Some Popular Surveys ### Employement Information - Sample surveys concerned with employment are carried out in most countries. Their frequency allows the study of trends over time and seasonality. - Their usefulness is often enhanced by piggybacking questions concerned with other subjects as in the case of the Australian Multi-Purpose Household Survey (Australia 2007). --- ## Some Popular Surveys ### Household sample survey Housing and household sample surveys can be particularly useful in countries that take a regular census. For instance, the English Housing Survey 2009–10 collected information on age, economic status, ethnicity and marital status and income of the household reference person. - It also provided information on household size and composition, and type of housing tenure (United Kingdom 2011). - Household sample surveys are conducted frequently to assess household income and expenditure, patterns, such as the Family Income and Expenditure Survey of Japan (Japan 2012). - Yet, other sample surveys collect data on a range of human activities including how people use their time (Australia 2008) --- # Big Data Sources - Data generated from digital sources - Examples: Social media platforms, mobile apps, online transactions - Provide real-time and large-scale data - Privacy and representativeness concerns --- # Conclusion - Demographic data comes from various sources - Each source has its strengths and limitations - Understanding the sources is crucial for data analysis and interpretation --- # References - Farhat Yusuf, Jo. M. Martins, David A. Swanson (auth.) - Methods of Demographic Analysis-Springer Netherlands (2014). - www.cartercenter.org