Matching Items (5)
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- All Subjects: Procurement
- Genre: Academic theses
- Creators: Sullivan, Kenneth
- Creators: Wiezel, Avi
- Creators: Enders, Stephen G
- Status: Published
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
Owner organizations in the architecture, engineering, and construction (AEC) industry are presented with a wide variety of project delivery approaches. Implementation of these approaches, while enticing due to their potential to save money, reduce schedule delays, or improve quality, is extremely difficult to accomplish and requires a concerted change management effort. Research in the field of organizational behavior cautions that perhaps more than half of all organizational change efforts fail to accomplish their intended objectives. This study utilizes an action research approach to analyze change message delivery within owner organizations, model owner project team readiness and adoption of change, and identify the most frequently encountered types of resistance from lead project members. The analysis methodology included Spearman's rank order correlation, variable selection testing via three methods of hierarchical linear regression, relative weight analysis, and one-way ANOVA. Key findings from this study include recommendations for communicating the change message within owner organizations, empirical validation of critical predictors for change readiness and change adoption among project teams, and identification of the most frequently encountered resistive behaviors within change implementation in the AEC industry. A key contribution of this research is the recommendation of change management strategies for use by change practitioners.
ContributorsLines, Brian (Author) / Sullivan, Kenneth (Thesis advisor) / Wiezel, Avi (Committee member) / Badger, William (Committee member) / Arizona State University (Publisher)
Created2014
Description
Qualifications based selection (QBS) of construction services uses a variety of criteria to evaluate proponents and select a contractor for the project. The criteria typically fall into three categories: past performance and technical capability, key personnel, and price, with price often being considered the most important factor in selection. Evaluation and the merits of the key personnel category is not well described or discussed in research. Prior research has investigated the evaluation criteria elements and their ability to differentiate proponents. This case study uses QBS evaluation data from fifty-eight construction projects to show that use of a structured interview process provides the highest level of differentiation of qualifications of proponents, as compared to the proposed price and the technical proposal. The results of the analysis also indicate: 1) the key personnel element (the interview) is statistically more important than price,
2) Contractors who propose on projects using QBS should use their best people in proposal response, and 3) Contractors should educate/prepare their teams for interviews, people count.
2) Contractors who propose on projects using QBS should use their best people in proposal response, and 3) Contractors should educate/prepare their teams for interviews, people count.
ContributorsSawyer, Jeff T (Author) / Sullivan, Kennth S (Thesis advisor) / Wiezel, Avi (Committee member) / Badger, William (Committee member) / Arizona State University (Publisher)
Created2014
Description
ABSTRACT
The current Saudi Arabian (SA) procurement system leads to many losses in money and benefits in projects. Also, the use of the traditional procurement system in SA has been identified as one of the causes for poor performance in the delivery of construction and the major risk to the SA government. A questionnaire has been developed and carefully designed based on literature review. The purpose of the survey was to identify the validity of the recent claims that the procurement system in SA is broken and to improve the current SA procurement system. The questionnaire was sent out to 1,396 participants including included 867 engineers, 256 consultants, 93 contractors, 35 owners and 132 architects and 13 academics.
All participants have been registered and licensed professionals at the SA Council for professional engineers, who work in both private and public sectors. The participants are interested in the SA procurement and contracts system with experience ranging from one to more than twenty-five years with the majority of twenty-five years of experience in common construction sectors such as; residential and commercial buildings, healthcare buildings, industrial building and heavy civil construction.
Most of the participants from both private and public sectors agreed with the survey questions subject matter regarding: zone price proposals, contractors' evaluation, risks, planning, projects' scope, owners concern and weekly risks reports (WRR). The survey results showed that the procurement system is the major risk to projects, affects construction projects negatively and is in need of improvement.
Based on the survey and literature review, a model, called Saudi government performance procurement model (SGPPM), has been developed in which the most expert contractor is chosen through four phases: submittals& education, vendors selection, illustration and execution. The resulting model is easy to implement by SA government and does not require special skills or backgrounds.
The current Saudi Arabian (SA) procurement system leads to many losses in money and benefits in projects. Also, the use of the traditional procurement system in SA has been identified as one of the causes for poor performance in the delivery of construction and the major risk to the SA government. A questionnaire has been developed and carefully designed based on literature review. The purpose of the survey was to identify the validity of the recent claims that the procurement system in SA is broken and to improve the current SA procurement system. The questionnaire was sent out to 1,396 participants including included 867 engineers, 256 consultants, 93 contractors, 35 owners and 132 architects and 13 academics.
All participants have been registered and licensed professionals at the SA Council for professional engineers, who work in both private and public sectors. The participants are interested in the SA procurement and contracts system with experience ranging from one to more than twenty-five years with the majority of twenty-five years of experience in common construction sectors such as; residential and commercial buildings, healthcare buildings, industrial building and heavy civil construction.
Most of the participants from both private and public sectors agreed with the survey questions subject matter regarding: zone price proposals, contractors' evaluation, risks, planning, projects' scope, owners concern and weekly risks reports (WRR). The survey results showed that the procurement system is the major risk to projects, affects construction projects negatively and is in need of improvement.
Based on the survey and literature review, a model, called Saudi government performance procurement model (SGPPM), has been developed in which the most expert contractor is chosen through four phases: submittals& education, vendors selection, illustration and execution. The resulting model is easy to implement by SA government and does not require special skills or backgrounds.
ContributorsAlofi, Ahmed Abdulrahman (Author) / Kashiwagi, Dean (Thesis advisor) / Sullivan, Kenneth (Committee member) / Kashiwagi, Jacob (Committee member) / Arizona State University (Publisher)
Created2017
Description
The objective of the study was to examine the impact construction document deficiencies have on heavy/civil low-bid infrastructure projects. It encompasses the expertise of 202 heavy/civil construction professionals comprised of contactors and public project owners. The study was designed to determine the frequency and timing of when a contractor discovers construction document deficiencies on heavy/civil low bid projects. The information was correlated with further study data of when a contractor ultimately reports the discovered construction document deficiencies to the public project owner. This research data was compiled and analyzed to determine if contractors are withholding construction document deficiencies from public owners until after the project contract has been executed. The withholding of document deficiencies can benefit contractors by resulting in additional owner incurred costs and potential justification for project time extensions. As a result, further research was required to examine the impact construction document deficiencies have on project cost and schedule. Based on the study findings, it has led to the development of a Contractor Document Review Assessment. The Contractor Document Review Assessment is a risk mitigation device in which contractors and public project owners can identify construction document deficiencies on heavy/civil low-bid construction projects before the project contract has been executed.
ContributorsPesek, Anthony Edward (Author) / Sullivan, Kenneth (Thesis advisor) / Badger, William (Committee member) / Bingham, Evan (Committee member) / Arizona State University (Publisher)
Created2017