Matching Items (5)
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- All Subjects: Robustness
- Creators: Anderies, John M
- Creators: Cham, Hei Ning
Description
Random Forests is a statistical learning method which has been proposed for propensity score estimation models that involve complex interactions, nonlinear relationships, or both of the covariates. In this dissertation I conducted a simulation study to examine the effects of three Random Forests model specifications in propensity score analysis. The results suggested that, depending on the nature of data, optimal specification of (1) decision rules to select the covariate and its split value in a Classification Tree, (2) the number of covariates randomly sampled for selection, and (3) methods of estimating Random Forests propensity scores could potentially produce an unbiased average treatment effect estimate after propensity scores weighting by the odds adjustment. Compared to the logistic regression estimation model using the true propensity score model, Random Forests had an additional advantage in producing unbiased estimated standard error and correct statistical inference of the average treatment effect. The relationship between the balance on the covariates' means and the bias of average treatment effect estimate was examined both within and between conditions of the simulation. Within conditions, across repeated samples there was no noticeable correlation between the covariates' mean differences and the magnitude of bias of average treatment effect estimate for the covariates that were imbalanced before adjustment. Between conditions, small mean differences of covariates after propensity score adjustment were not sensitive enough to identify the optimal Random Forests model specification for propensity score analysis.
ContributorsCham, Hei Ning (Author) / Tein, Jenn-Yun (Thesis advisor) / Enders, Stephen G (Thesis advisor) / Enders, Craig K. (Committee member) / Mackinnon, David P (Committee member) / Arizona State University (Publisher)
Created2013
Description
For this thesis a Monte Carlo simulation was conducted to investigate the robustness of three latent interaction modeling approaches (constrained product indicator, generalized appended product indicator (GAPI), and latent moderated structural equations (LMS)) under high degrees of nonnormality of the exogenous indicators, which have not been investigated in previous literature. Results showed that the constrained product indicator and LMS approaches yielded biased estimates of the interaction effect when the exogenous indicators were highly nonnormal. When the violation of nonnormality was not severe (symmetric with excess kurtosis < 1), the LMS approach with ML estimation yielded the most precise latent interaction effect estimates. The LMS approach with ML estimation also had the highest statistical power among the three approaches, given that the actual Type-I error rates of the Wald and likelihood ratio test of interaction effect were acceptable. In highly nonnormal conditions, only the GAPI approach with ML estimation yielded unbiased latent interaction effect estimates, with an acceptable actual Type-I error rate of both the Wald test and likelihood ratio test of interaction effect. No support for the use of the Satorra-Bentler or Yuan-Bentler ML corrections was found across all three methods.
ContributorsCham, Hei Ning (Author) / West, Stephen G. (Thesis advisor) / Aiken, Leona S. (Committee member) / Enders, Craig K. (Committee member) / Arizona State University (Publisher)
Created2010
Description
The coastal fishing community of Barrington, Southwest Nova Scotia (SWNS), has depended on the resilience of ocean ecosystems and resource-based economic activities for centuries. But while many coastal fisheries have developed unique ways to govern their resources, global environmental and economic change presents new challenges. In this study, I examine the multi-species fishery of Barrington. My objective was to understand what makes the fishery and its governance system robust to economic and ecological change, what makes fishing households vulnerable, and how household vulnerability and system level robustness interact. I addressed these these questions by focusing on action arenas, their contexts, interactions and outcomes. I used a combination of case comparisons, ethnography, surveys, quantitative and qualitative analysis to understand what influences action arenas in Barrington, Southwest Nova Scotia (SWNS). I found that robustness of the fishery at the system level depended on the strength of feedback between the operational level, where resource users interact with the resource, and the collective-choice level, where agents develop rules to influence fishing behavior. Weak feedback in Barrington has precipitated governance mismatches. At the household level, accounts from harvesters, buyers and experts suggested that decision-making arenas lacked procedural justice. Households preferred individual strategies to acquire access to and exploit fisheries resources. But the transferability of quota and licenses has created divisions between haves and have-nots. Those who have lost their traditional access to other species, such as cod, halibut, and haddock, have become highly dependent on lobster. Based on regressions and multi-criteria decision analysis, I found that new entrants in the lobster fishery needed to maintain high effort and catches to service their debts. But harvesters who did not enter the race for higher catches were most sensitive to low demand and low prices for lobster. This study demonstrates the importance of combining multiple methods and theoretical approaches to avoid tunnel vision in fisheries policy.
ContributorsBarnett, Allain J. D (Author) / Anderies, John M (Thesis advisor) / Abbott, Joshua K (Committee member) / Bolin, Bob (Committee member) / Eakin, Hallie (Committee member) / Arizona State University (Publisher)
Created2014
Description
Anderies (2015); Anderies et al. (2016), informed by Ostrom (2005), aim to employ robust
feedback control models of social-ecological systems (SESs), to inform policy and the
design of institutions guiding resilient resource use. Cote and Nightingale (2012) note that
the main assumptions of resilience research downplay culture and social power. Addressing
the epistemic gap between positivism and interpretation (Rosenberg 2016), this dissertation
argues that power and culture indeed are of primary interest in SES research.
Human use of symbols is seen as an evolved semiotic capacity. First, representation is
argued to arise as matter achieves semiotic closure (Pattee 1969; Rocha 2001) at the onset
of natural selection. Guided by models by Kauffman (1993), the evolution of a symbolic
code in genes is examined, and thereon the origin of representations other than genetic
in evolutionary transitions (Maynard Smith and Szathmáry 1995; Beach 2003). Human
symbolic interaction is proposed as one that can support its own evolutionary dynamics.
The model offered for wider dynamics in society are “flywheels,” mutually reinforcing
networks of relations. They arise as interactions in a domain of social activity intensify, e.g.
due to interplay of infrastructures, mediating built, social, and ecological affordances (An-
deries et al. 2016). Flywheels manifest as entities facilitated by the simplified interactions
(e.g. organizations) and as cycles maintaining the infrastructures (e.g. supply chains). They
manifest internal specialization as well as distributed intention, and so can favor certain
groups’ interests, and reinforce cultural blind spots to social exclusion (Mills 2007).
The perspective is applied to research of resilience in SESs, considering flywheels a
semiotic extension of feedback control. Closer attention to representations of potentially
excluded groups is justified on epistemic in addition to ethical grounds, as patterns in cul-
tural text and social relations reflect the functioning of wider social processes. Participatory
methods are suggested to aid in building capacity for institutional learning.
feedback control models of social-ecological systems (SESs), to inform policy and the
design of institutions guiding resilient resource use. Cote and Nightingale (2012) note that
the main assumptions of resilience research downplay culture and social power. Addressing
the epistemic gap between positivism and interpretation (Rosenberg 2016), this dissertation
argues that power and culture indeed are of primary interest in SES research.
Human use of symbols is seen as an evolved semiotic capacity. First, representation is
argued to arise as matter achieves semiotic closure (Pattee 1969; Rocha 2001) at the onset
of natural selection. Guided by models by Kauffman (1993), the evolution of a symbolic
code in genes is examined, and thereon the origin of representations other than genetic
in evolutionary transitions (Maynard Smith and Szathmáry 1995; Beach 2003). Human
symbolic interaction is proposed as one that can support its own evolutionary dynamics.
The model offered for wider dynamics in society are “flywheels,” mutually reinforcing
networks of relations. They arise as interactions in a domain of social activity intensify, e.g.
due to interplay of infrastructures, mediating built, social, and ecological affordances (An-
deries et al. 2016). Flywheels manifest as entities facilitated by the simplified interactions
(e.g. organizations) and as cycles maintaining the infrastructures (e.g. supply chains). They
manifest internal specialization as well as distributed intention, and so can favor certain
groups’ interests, and reinforce cultural blind spots to social exclusion (Mills 2007).
The perspective is applied to research of resilience in SESs, considering flywheels a
semiotic extension of feedback control. Closer attention to representations of potentially
excluded groups is justified on epistemic in addition to ethical grounds, as patterns in cul-
tural text and social relations reflect the functioning of wider social processes. Participatory
methods are suggested to aid in building capacity for institutional learning.
ContributorsBožičević, Miran (Author) / Anderies, John M (Thesis advisor) / Bolin, Robert (Committee member) / BurnSilver, Shauna (Committee member) / Arizona State University (Publisher)
Created2017
Description
Sustainability depends in part on our capacity to resolve dilemmas of the commons in Coupled Infrastructure Systems (CIS). Thus, we need to know more about how to incentivize individuals to take collective action to manage shared resources. Moreover, given that we will experience new and more extreme weather events due to climate change, we need to learn how to increase the robustness of CIS to those shocks. This dissertation studies irrigation systems to contribute to the development of an empirically based theory of commons governance for robust systems. I first studied the eight institutional design principles (DPs) for long enduring systems of shared resources that the Nobel Prize winner Elinor Ostrom proposed in 1990. I performed a critical literature review of 64 studies that looked at the institutional configuration of CIS, and based on my findings I propose some modifications of their definitions and application in research and policy making. I then studied how the revisited design principles, when analyzed conjointly with biophysical and ethnographic characteristics of CISs, perform to avoid over-appropriation, poverty and critical conflicts among users of an irrigation system. After carrying out a meta-analysis of 28 cases around the world, I found that particular combinations of those variables related to population size, countries corruption, the condition of water storage, monitoring of users behavior, and involving users in the decision making process for the commons governance, were sufficient to obtain the desired outcomes. The two last studies were based on the Peruvian Piura Basin, a CIS that has been exposed to environmental shocks for decades. I used secondary and primary data to carry out a longitudinal study using as guidance the robustness framework, and different hypothesis from prominent collapse theories to draw potential explanations. I then developed a dynamic model that shows how at the current situation it is more effective to invest in rules enforcement than in the improvement of the physical infrastructure (e.g. reservoir). Finally, I explored different strategies to increase the robustness of the system, through enabling collective action in the Basin.
ContributorsRubinos, Cathy (Author) / Anderies, John M (Thesis advisor) / Abbott, Joshua K (Committee member) / Janssen, Marcus A (Committee member) / Arizona State University (Publisher)
Created2017