Missing(ness) in Action : Selectivity Bias in GPS-Based Land Area Measurements

Missing(ness) in Action : Selectivity Bias in GPS-Based Land Area Measurements

Land area is a fundamental component of agricultural statistics, and of analyses undertaken by agricultural economists. While household surveys in developing countries have traditionally relied on farmers' own, potentially error-prone, land ar...

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Bibliographic Details
Main Authors: Kilic, Talip, Zezza, Alberto, Carletto, Calogero, Savastano, Sara
Format: Policy Research Working Paper
Language:English
en_US
Published: World Bank, Washington, DC 2013
Subjects:
AGRICULTURAL OUTPUT
AGRICULTURE
COMMODITY
COMPUTATION
CONFIDENCE INTERVALS
COVARIANCE
COVARIANCE MATRIX
DATA ANALYSES
DATA ANALYSIS
DATA COLLECTION
DATA ENTRY
DESCRIPTIVE STATISTICS
DEVELOPMENT ECONOMICS
DEVELOPMENT POLICY
DEVELOPMENT RESEARCH
DEVELOPMENT STRATEGIES
DOMAIN
DOMAINS
ECONOMIC DEVELOPMENT
ECONOMIC INEQUALITY
ENUMERATION
EQUIPMENT
EXPERIMENTS
EXPLORATION
FIELD WORK
FINANCIAL RESOURCES
FINANCIAL SUPPORT
GLOBAL POSITIONING SYSTEM
GPS
GROSS VALUE
HUMAN RESOURCES
HYPOTHESIS TESTING
IMPLEMENTING AGENCIES
IMPUTATION METHOD
IMPUTATION METHODS
IMPUTATION PROCESS
IMPUTATIONS
INCOME
INDEPENDENT VARIABLES
INNOVATION
LINEAR PREDICTION
LINEAR REGRESSION
LIVING STANDARDS
MEASUREMENT ERRORS
MISSING DATA
MISSING OBSERVATIONS
MISSING VALUE
MISSING VALUES
MULTIPLE IMPUTATION
OPEN ACCESS
OPPORTUNITY COSTS
POLITICAL ECONOMY
PRECISION
PREDICTIONS
PROBABILITY
PRODUCTION FUNCTION
PRODUCTIVITY
PROPERTY RIGHTS
PROTOCOL
PROTOCOLS
QUALITY CONTROL
QUESTIONNAIRES
RESEARCH METHODS
RESEARCH REPORT
RESEARCH WORKING PAPERS
RESEARCHERS
RESULT
RESULTS
SAMPLE SIZE
SAMPLE SURVEYS
SATELLITE
SCIENCES
SENSITIVITY ANALYSIS
SIMULATIONS
SOFTWARE PACKAGES
STANDARD ERRORS
STANDARD MEASUREMENT
STATA
STATISTICAL ANALYSES
STATISTICAL INFERENCE
STATISTICAL TECHNIQUES
STATISTICIANS
SUPERVISION
SURPLUS LABOR
SURVEY DATA
SURVEY DESIGN
SURVEYORS
TECHNOLOGICAL INNOVATIONS
TOTAL FACTOR PRODUCTIVITY
TOTAL OUTPUT
TRANSITION ECONOMY
USE VALUE
USERS
VALIDITY
VALUE OF OUTPUT
VARIABILITY
WEALTH
WEB
WEIGHTING
land area measurement
land productivity
Online Access:http://documents.worldbank.org/curated/en/2013/06/17875976/missingness-action-selectivity-bias-gps-based-land-area-measurements
http://hdl.handle.net/10986/15849
Description
Summary:Land area is a fundamental component of agricultural statistics, and of analyses undertaken by agricultural economists. While household surveys in developing countries have traditionally relied on farmers' own, potentially error-prone, land area assessments, the availability of affordable and reliable Global Positioning System (GPS) units has made GPS-based area measurement a practical alternative. Nonetheless, in an attempt to reduce costs, keep interview durations within reasonable limits, and avoid the difficulty of asking respondents to accompany interviewers to distant plots, survey implementing agencies typically require interviewers to record GPS-based area measurements only for plots within a given radius of dwelling locations. It is, therefore, common for as much as a third of the sample plots not to be measured, and research has not shed light on the possible selection bias in analyses relying on partial data due to gaps in GPS-based area measures. This paper explores the patterns of missingness in GPS-based plot areas, and investigates their implications for land productivity estimates and the inverse scale-land productivity relationship. Using Multiple Imputation (MI) to predict missing GPS-based plot areas in nationally-representative survey data from Uganda and Tanzania, the paper highlights the potential of MI in reliably simulating the missing data, and confirms the existence of an inverse scale-land productivity relationship, which is strengthened by using the complete, multiply-imputed dataset. The study demonstrates the usefulness of judiciously reconstructed GPS-based areas in alleviating concerns over potential measurement error in farmer-reported areas, and with regards to systematic bias in plot selection for GPS-based area measurement.

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