1 Introduction to Sampling : Censuses vs. Sample Surveys Module 3 Session 4.
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Transcript of 1 Introduction to Sampling : Censuses vs. Sample Surveys Module 3 Session 4.
![Page 1: 1 Introduction to Sampling : Censuses vs. Sample Surveys Module 3 Session 4.](https://reader033.fdocuments.in/reader033/viewer/2022051613/5515f9a455034694308b488f/html5/thumbnails/1.jpg)
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Introduction to Sampling: Censuses vs.
Sample Surveys
Module 3
Session 4
![Page 2: 1 Introduction to Sampling : Censuses vs. Sample Surveys Module 3 Session 4.](https://reader033.fdocuments.in/reader033/viewer/2022051613/5515f9a455034694308b488f/html5/thumbnails/2.jpg)
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Session Objectives
Distinguish between censuses and sample surveys Demonstrate the linkages between censuses and
surveys Discuss the challenges of conducting censuses and
large scale surveys in Uganda Distinguish between random and non random samples Identify the types and/or sources of errors in censuses
and surveys Discuss how errors can be minimised in censuses and
surveys
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Reminder of Definitions
Population: totality of all units of interest Sample: part/subset of the population Censuses: inquiries that cover the whole population eg.
Uganda Population and Housing Census, CIS, EMIS, HMIS, LOGICS, etc
Sample surveys are inquiries that cover part/subset of the population eg. UDHS, UNHS, NSDS, etc
Sampling Frame: list of distinct and distinguishable units in the population of interest; beginning step in almost all random sampling schemes, e.g. numbers written on households before the census night
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Other Definitions
Defacto census- covers all persons found within the borders of a particular territory/country at a particular point in time-census night
Dejure census-tallies people according to their regular or legal residence
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Sampling Frames
Sources Administrative records-eg
Hospital records Birth and Death Registers LC lists Voters’ register School registers etc
Construct your own
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Disadvantages of various sources of sampling frames
Administrative records may not be up to date
Constructing your own may be too costly especially in large scale surveys
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Role of censuses in Uganda
Provide benchmark data for monitoring, planning and policy formulation eg we need data for UPE monitoring, poverty monitoring Election monitoring Resource allocation
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Role of censuses in Uganda (cont.)
Provide small area statistics - basic data disaggregated to the lowest administrative unit e.g we use census data to know the number of people in each village, sub county and district for planning purposes
Show the actual status of the various indicators
Health indicators-mortality, disease prevalence
Fertility trends, population growth rate
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Linkages between censuses and sample surveys
Sample surveys can be used as a substitute for censuses
Sample surveys can be used to supplement census data
Sample surveys can be used to pretest census materials, procedures and methods
Censuses are used as a basis for surveys conducted between censuses
Sample surveys can be used to monitor census results
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Challenges of Conducting Censuses and Large Scale Sample Surveys
Challenges of Surveys and Censuses Mubiru James.ppt
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Types of Samples
There two types of samples: Random and Non random samples
Random samples are those whose composition is not influenced by the sampler
Non Random samples are those whose composition is influenced by the sampler
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Advantages of Random Samples
Objective and hence inferences based on them are reliable
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Disadvantages of Random Samples
Costly to select Need skilled manpower to get a random
sample For some surveys, random sampling may not
be the best because the sample may not provide the required data.
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Advantages of Non Random Samples
Easy and cheap to select since selection and substitution can be done at will
Since they are done at will, the data needed can be easily obtained
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Disadvantages of Non Random Samples
Subjective and hence inferences based on them are biased
Sampling errors can not be estimated
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Types of Errors
There are two types of errors, namely: Sampling errors Non sampling errors
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Sampling Errors/Biases
Sampling errors are absent in censuses Their causes include:
Use of defective sampling frame Use of defective sampling procedures Use of an estimation method that does not
correspond to the sampling design
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Non Sampling Errors
Non sampling errors occur both in censuses and sample surveys but are more pronounced in censuses
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Sources of Non sampling Errors
Defective sampling frames resulting into coverage errors Under coverage Over coverage
Conceptual problems Physical environment Inadequacy of enumerators and supervisors
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Sources continued
Language problems – translation Problems of measurement Response problems Non response problems Poor cartographic work Poorly designed questionnaires/instruments Poorly trained enumerators/supervisors Unqualified enumerators/supervisors
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How Errors can be Minimised
Supervision Training Use of the appropriate estimation method Publicity of the survey Testing the survey instruments
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Sampling in the Research Process
Problem Objectives Hypotheses Methodology
Data Sources Target population
Census or sample? If sample?
What is the sampling design?