Sample Issues and Field Work

Session VLusaka, January 20, 2003Juan Munoz and Francesca Recanatiniwww.worldbank.org/wbi/governance

MotivationThe team has defined:

The purpose of the assessmentThe variables to studyThe empirical tool to useThe process to employ

But, who should be targeted?

Basic DefinitionsSampling allows to measure characteristics of a population, when accessing the whole population is not possible because of economic, practical or physical considerations.

Sampling allows to select a subset of a population to study a specific issue in a meaningful way

Basic DefinitionsPopulation: the sum of all the observations within a specified setTarget population: all statistical units of interest for the purposes of analysis Working population: all statistical units that can be surveyed

Basic Sampling Techniques

The three basic techniques of probability sampling:

Simple Random SamplingMulti-stage SamplingStratified Sampling

Most household and firm surveys use a combination of these three techniques.

Assuring good field work

What happens when fieldwork is poor?

A long and frustrating process of “data cleaning” becomes unavoidableThe data loose their policy-making relevance

Data quality is not guaranteedThe process converges (at best) to databases that are internally consistent

The process entails a myriad of decisions, generally undocumentedUsers mistrust the data

Key factorsManage the survey as an integrated projectImplement the team concept in the organization of field operationsIntegrate computer-based quality controls to field operationsEstablish strong supervision proceduresEnsure sufficient trainingWork with a reduced staff over an extended period of data collection

Management levelsCore staff

Survey managerField operations managerData manager

Tactical options for the organization of field teams

Mobile teams with fixed data entryMobile teams with integrated data entrySometime in the future: the paperless interview

Mobile teams with fixed data entryCote d’Ivoire (1984)Peru (1985)GhanaPakistanGuinea-ConakryMozambique

Composition of a field team

Supervisor Interviewers Data entry

operator

The team and its tools

Supervisor Interviewers Data entryoperator

Antropo-

metrist

Two PSUs visited in a four-week period

Alama Bamako

Regional Office

First weekAlama Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

First weekAlama Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

First weekAlama

Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

First weekAlama Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

First weekAlama Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

First weekAlama Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

They complete

first half of questionnair

es in all selected

households

First weekAlama Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

First weekAlama Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to

Alama

First weekAlama

Bamako

Regional Office

Operator remains in Regional

OfficeRest of the

team travels to Alama and

back

First weekAlama Bamako

Regional Office

Supervisor gives Alama questionnair

es to DEO

Rest of the team

travels to Alama and

back

Second weekAlama Bamako

Regional Office

Operator enters first

week data from Alama

Rest of the team

travels to Bamako

Second weekAlama

Bamako

Regional Office

Operator enters first

week data from Alama

Rest of the team

travels to Bamako

Second weekAlama

Bamako

Regional Office

Operator enters first

week data from Alama

Rest of the team

travels to Bamako

They complete

first half of questionnair

es in all selected

households

Second weekAlama Bamako

Regional Office

Operator enters first

week data from Alama

Rest of the team

travels to Bamako and back

Second weekAlama

Bamako

Regional Office

Supervisor gives

Bamako questionnaires to DEO. DEO gives

back Alama questionnair

es with flagged

inconsistencies

Rest of the team

travels to Bamako and back

Third weekAlama

Bamako

Regional Office

Operator enters first week data from Bamako

Team completes second half of

questionnaires. They correct

inconsistencies from first half

Fourth weekAlama Bamako

Regional Office

Operator enters second week data

from Alama. Corrects

inconsistencies from first round

Team completes second half of

questionnaires. They correct

inconsistencies from first half

Fourth week

Regional Office

The result is a clean data set on

diskette, ready for analysis

immediately after data collection

Mobile teams with integrated data entryNepal (1992)ArgentinaParaguayBangladesh (2000)

Mobile teams with integrated data entry

Regional Office

Alama

Bamako

CocodyTeam works with

portable computers and

printers

Mobile teams with integrated data entry

Regional Office

Alama

Bamako

CocodyOperator travels with the rest of the field team

Mobile teams with integrated data entry

Regional Office

Alama

Bamako

Cocody

Data entry and validation almost

immediate

Mobile teams with integrated data entry

Regional Office

Alama

Bamako

Cocody

Reduced trips to and from

Regional Office to selected PSUs

Mobile teams with integrated data entry

Regional Office

Alama

Bamako

Cocody

Benefits of integrationProvides reliable and timely databasesProvides immediate feedback on the performance of the field staff, allowing early detection of inadequate behaviorsEnsures that all field staff applies uniform criteria throughout the full period of data collection Solves inconsistencies through direct verification of households reality, rather that through office guessworkIs consistent with the total quality culture

Supervision tasks

Verification of questionnaires for completenessRandom re-interviews of householdsObservation of interviews

Selecting and training field staff

Why is it importantHow long does it takeHow is it organized

Example: Day 2 of interviewer training for household survey

Definition of household (and dwelling, family, etc.)Pictorial of a sample householdSlide with an empty roster (explain case conventions, encoding, skip patterns, etc.)

Example, cont.

Fill the roster for the sample household (need for legible handwriting, recording of ages, use of a calendar of events, etc.)Role playing (trainer as a respondent, simulating borderline cases)Role playing (trainees interview each other)