Basic Concepts and an Example John Antle Roberto Valdivia Agricultural and Resource Economics Oregon State University wwwtradeoffsoregonstateedu What is the TOAMD Model The TOAMD ID: 462202
Download Presentation The PPT/PDF document "What is the TOA-MD Model?" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
What is the TOA-MD Model? Basic Concepts and an ExampleJohn AntleRoberto ValdiviaAgricultural and Resource EconomicsOregon State Universitywww.tradeoffs.oregonstate.eduSlide2
What is the TOA-MD Model? The TOA-MD Model is a unique simulation tool for multi-dimensional impact assessment that uses a statistical description of a heterogeneous farm population to simulate the adoption and impacts of a new technology or a change in environmental conditions. TOA-MD is designed to simulate what would be observed if it were possible to conduct a controlled experiment. In this experiment, a population of farms is offered the choice of continuing to use the current or “base” production system (System 1), or choosing to adopt a new system (System 2).
In fact it is never possible to carry out such ideal experiments, so TOA-MD is designed to utilize the available data to attain the best possible approximation, given the available time and other resources available to conduct the analysis.
Additionally, TOA-MD is designed to facilitate analysis of the inevitable uncertainties associated with impact assessment. Slide3
There are two components in the TOA-MD analysis: First, the model simulates the proportion of farms that would adopt a new system (system 2), and the proportion that would continue to use the “base” system (system 1) Second, based on the adoption rate of the system 2, the TOA-MD model simulates selected economic, environmental and social impact indicators for adopters, non-adopters and the entire population.Slide4
How is the TOA-MD simulation approach related to the experimental and non-experimental statistical approach to impact assessment (estimation of “treatment effects”)? The underlying conceptual model is very similar: economic agents (farms in this case) self-select into “treatment” or choose to adopt a technology (or adapt to an exogenous change such as climate change), and related “outcomes” occur to those self-selected into “treatment” (adoption) For “ex post” assessment the simulation approach can be used together with experimental methods to parameterize the model and simulate outcomes of interest, including both “mean” indicators and other “threshold” indicators such as poverty rates and indicators based on other quantifiable outcomes. It can also be used to simulate “policy relevant” effects, such as technology adoption induced by payments for ecosystem services. For “ex ante” assessment, where statistical methods cannot be used, the simulation approach provides a “laboratory” to explore potential impacts, using various types of available data to construct the future “counterfactual,” e.g., the impacts of and adaptation to climate change.Slide5
TOA-MD approach: modeling systems used by heterogeneous populationsSystems are being used in heterogeneous populationsA system is defined in terms of household, crop, livestock and aquaculture sub-systemsSlide6
(
ω
)
0
Map of a heterogeneous region
Opportunity cost, system choice and adoption
Opportunity cost = v
1
– v
2
follows distribution ()
v
1
= returns to system 1
V
2
= returns to system 2
System 1: > 0
(non-adopters)
System 2: < 0 (adopters)
opportunity costSlide7
Outcome distributions are associated with system choiceFarms select themselves into “non-adopter” and “adopter” sub-populations, generating corresponding outcome distributions for these sub-populations Impact indicators are based on system choice and outcome distributionsTOA-MD produces mean indicators and threshold-based indicatorsAnalysis shows that impacts depend on the correlations between adoption (opportunity cost) and outcomesMany impact assessments ignore correlationsYet these correlations are often important for accurate impact assessment!Adoption, Outcome Distributions and Impact IndicatorsSlide8
Adoption and outcome distributions
Entire Population with adoption: 55% >
r(1,
a
)% non-adopters
System 1: 20% >
System 1 before adoption:
25% > threshold
System 2: 90% >
Outcome
z
(
z
|1)
r(2,
a
)% adopters
(
z
|1,a)
(
z
|2,
a
)
(
z
|a
)Slide9
Components of TOA-MD AnalysisSystem characterizationAdoption rate Population (Strata)
Impact indicator design
Opportunity cost distribution
Outcome distributions
Indicators and Tradeoffs
Design
Data
SimulationSlide10
An Example: Integrated Agriculture-Aquaculture Based on Dey et al (2010) Agricultural Economics: economic analysis of IAA stratified survey of farms, without and with IAA Design of TOA-MD analysis population: farm households in southern Malawi where aquaculture is feasible
strata: 5 southern districts
systems:
Subsistence crops
Crops + aquaculture, low or high integration
Subsistence crops
Aquaculture
Irrigated vegetablesSlide11
Adoption Rate and Opportunity Cost of Adopting IAA in Southern Malawi – Predicted Adoption Rate is Point Where Curves Cross the Horizontal AxisSlide12
Poverty Rate and Adoption Rate of IAA, Southern Malawi Slide13
Mean Monthly Protein Consumption and Adoption of IAA, Southern MalawiNote most improvement occurs for those districts with lowest protein consumptionSlide14
Relationship between adoption and Protein Consumption, Non-adopters and Adopters of IAA, Mulanje Dist., MalawiNon-adopter sub-population and entire population are equal at 0% adoption
Adopter sub-population and entire population are equal at 100% adoption
Slope of relationship between indicator and adoption rate has same sign as the correlation between opp cost and the outcome variable (negative in this case)Slide15
Relationship between adoption and Mean Returns per Farm, Non-Adopters and Adopters of IAA, Mulanje District, MalawiEconomic outcomes that are positively related to net returns have a maximum in the entire population at the predicted adoption rate (41% in this example)Slide16
The various “treatment effects” discussed in the experimental and non-experimental statistical literatures are either equivalent to or closely related to the mean indicators generated by the TOA-MD model: AveTreatment Effect = mean population indicator
Marginal Treatment Effect = change in mean indicator
Treatment on Treated = related to mean indicator of adopters
Treatment on Untreated = related to mean indicator of non-adopters
Policy relevant treatment effect = derived from mean indicatorsSlide17
Summary: Impacts of IAA Adoption on Farm Population and IAA AdoptersSlide18
Conclusions TOA-MD is a unique simulation tool for multi-dimensional impact assessment of agricultural systems The Malawi case study illustrates how it can be used with available data to simulate: the adoption rate of a new technology the economic, environmental or social impacts of the new technology The model can also be used for analysis of ecosystem services, and impacts of climate change and other environmental change Training in use of the model, and the model software are available from the TOA Team.Slide19
More info is available at : http://tradeoffs.oregonstate.edu