Module 3 Session 04

8/17/2019 Module 3 Session 04

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Introduction to Sampling

: Censuses vs.Sample Surveys

Module 3

Session 4


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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 largescale surveys in Uganda

Distinguish between random and non random samples

Identify the types andor 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: partsubset of the population

Censuses: in!uiries that cover the whole population eg"

Uganda #opulation and $ousing %ensus& %IS& 'MIS& $MIS&()*I%S& etc

Sample surveys are in!uiries that cover partsubset of the

population eg" UD$S& U+$S& +SDS& etc

Sampling Frame: list of distinct and distinguishable units inthe 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

territorycountry at a particular point in time-

census night

De.ure census-tallies people according to

their regular or legal residence


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Sampling Frames

Sources 0dministrative records-eg $ospital records

1irth and Death egisters

(% lists

oters register

School registers etc

%onstruct your own


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Disadvantages of various

sources of sampling frames

0dministrative records may not be up to

date

%onstructing your own may be too costlyespecially in large scale surveys


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Role of censuses in ganda

#rovide benchmark data for monitoring&planning and policy formulation eg we needdata for U#' monitoring& poverty monitoring 'lection monitoring esource allocation


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Role of censuses in ganda

!cont."

#rovide small area statistics - basic datadisaggregated to the lowest administrativeunit e"g we use census data to know the

number of people in each village& sub countyand district for planning purposes

Show the actual status of the various

indicators$ealth indicators-mortality& disease

prevalence8ertility trends& population growth rate


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#in$ages bet%een censuses

and sample surveys

Sample surveys can be used as a substitute forcensuses

Sample surveys can be used to supplement

census data Sample surveys can be used to pretest census

materials& procedures and methods %ensuses 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 #arge Scale Sample

Surveys

%hallenges of Surveys and %ensuses Mubiru


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&ypes of Samples

=here two types of samples>

andom and +on random samples

andom samples are those whose

composition is not influenced by the sampler

+on andom samples are those whosecomposition is influenced by the sampler


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'dvantages of Random

Samples

)b.ective and hence inferences based on

them are reliable


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Disadvantages of Random

Samples

%ostly to select

+eed skilled manpower to get a random

sample 8or some surveys& random sampling may not

be the best because the sample may not

provide the re!uired data"


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'dvantages of (on Random

Samples

'asy and cheap to select since selection and

substitution can be done at will

Since they are done at will& the data neededcan be easily obtained


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Disadvantages of (on Random

Samples

Sub.ective and hence inferences based on

them are biased

Sampling errors can not be estimated


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&ypes of )rrors

=here are two types of errors& namely> Sampling errors

+on sampling errors


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Sampling )rrors*+iases

Sampling errors are absent in censuses

=heir 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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(on Sampling )rrors

+on sampling errors occur both in censuses

and sample surveys but are more

pronounced in censuses


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Sources of (on sampling

)rrors

Defective sampling frames resulting into

coverage errors Under coverage

)ver coverage

%onceptual problems

#hysical environment

Inade!uacy of enumerators and supervisors


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2:

,o% )rrors can be -inimised

Supervision

=raining

Use of the appropriate estimation method#ublicity of the survey

=esting the survey instruments


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Sampling in the Research

rocess

#roblem)b.ectives$ypothesesMethodology Data Sources =arget population

%ensus or sample@ If sample@ Ahat is the sampling design@

Module 3 Session 04

Documents

Transcript of Module 3 Session 04