Bivariate Ordered Probit Analysis of Public Attitudes Toward Multifunctionality of Agriculture in the U.S.

Agricultural and Food Policy,

Discrete choice models, which one performs better?

For over the last thirty years the multinomial logit model has been the standard in choice modeling. Development in econometrics and computational algorithms has led to the increasing tendency to opt for more flexible models able to depict more realistically choice behavior. This study compares three discrete choice models, the standard multinomial logit, the error components logit, and the random parameters logit. Data were obtained from two choice experiments conducted to investigate consumers’ preferences for fresh pears receiving several postharvest treatments. Model comparisons consisted of in-sample and holdout sample evaluations. Results show that product characteristics hence, datasets, influence model performance. We also found that the multinomial logit model outperformed in at least one of three evaluations in both datasets. Overall, findings signal the need for further studies controlling for context and dataset to have more conclusive cues for discrete choice models capabilities.multinomial logit model, error components, random parameters, discrete choice, Research Methods/ Statistical Methods, C25, D12,

Health Concerns and Consumer Preferences for Soy Foods: Choice Modeling Approach

Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

Three essays on modeling consumer demand

Scope, Method of Study, and Findings: Although stated preference data obtained through real and hypothetical surveys and experiments are increasingly being used in economic research, there remain doubts about the validity of preference elicitation methods and econometric models used to estimate consumer preferences. This study explores such doubts and provides richer understanding of consumer demand.The first essay compared the ability of three preference elicitation methods (hypothetical choices, non-hypothetical choices, and non-hypothetical rankings) and three discrete-choice econometric models (the multinomial logit [MNL], the independent availability logit [IAL], and the random parameter logit [RPL]) to predict actual retail shopping behavior in three different product categories (ground beef, wheat flour, and dishwashing liquid). Overall, this study found a high level of external validity. Specific results suggested that the non-hypothetical elicitation approaches, especially the non-hypothetical ranking method, outperformed the hypothetical choice experiment in predicting retail sales. This study also found that the RPL can have superior predictive performance, but that the MNL predict equally well in some circumstances.Although experimental studies have reported a wide array of other-regarding behavior, the pervasiveness of such behavior in the field is an open question. Using a stated preference experiment, the second essay first estimated people's preferences, when purchasing food products, for the distribution of benefits accruing to participants in the food supply chain. Although none of the existing fairness models exhibit much predictive power, this study found that people are in-fact concerned about the distribution of benefits resulting from food purchases, and that modifications to the models to fit the food context significantly improves explanatory power. Finally, this study found that the measured preferences, along with elicited beliefs are significant predictors of people's willingness-to-pay a premium for organic food.RPL or mixed logit models are increasingly being reported in the literature, but uncertainties about the reliability of the model remain. Using Monte Carlo simulations, the third paper found that mixed logit estimates exhibit bias in small samples (N=200); an effect that dissipates as sample size increases. Despite the fact that the conventional multinomial logit is a restricted form of the mixed logit, simulation results indicate that if there is no preference heterogeneity, the conventional multinomial logit provides much more efficient estimates than the mixed logit. Moreover, in large samples there is a high likelihood of observing type I errors - finding statistically significant heterogeneity when none exists. Finally, simulation results indicate differences in performance across commercial software package providing mixed logit estimation routines

Understanding The Impact Of IT Service Innovation On Firm Performance: The Case Of Cloud Computing

Recently we have witnessed a new kind of IT advancement. It is a phenomenon where various types of IT capabilities are centralized into data centers to ensure that such resources are available wherever and whenever they are needed. Cloud computing is the latest version of IT service practice reflecting such new IT trends. Although cloud computing is considered a paradigm shift of IT service design and delivery in IS communities and intrigues large amounts of interest from business entities, few studies have examined this new IT and business phenomenon. To better understand the organizational application of cloud computing, the current study aims to investigate economic payoff from cloud computing investment. Employing the event study methodology, we analyze 183 firm-level announcements regarding cloud computing adoption. The results indicate that cloud computing adoption announcements are associated with positive increases in the market value of the firm. In addition, we identified differences in the effect of cloud computing adoption on market returns according to strategic adoption intention, firm size, and industry sector. These results can be used as useful references for the firm’s decision-making about whether, when, and how to adopt cloud computing to maximize its business value

Usefulness of prone cross-table lateral radiographs in vertebral compression fractures

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Dynamic radiographs are recommended to investigate non-healing evidence such as the dynamic mobility or intravertebral clefts in osteoporotic vertebral compression fractures (VCFs). However, it is difficult to examine standing flexion and extension lateral radiographs due to severe pain. The use of prone cross-table lateral radiographs (PrLRs) as a diagnostic tool has never been proposed to our knowledge. The purpose of this study is to clarify the usefulness of PrLRs in diagnosis and treatment of VCFs. Methods: We reviewed 62 VCF patients examined with PrLRs between January 1, 2008 and June 30, 2011. To compare the degree of pain provoked between standing extension lateral radiographs (StLRs) and PrLRs, numeric rating scale (NRS) scores were assessed and compared by a paired t-test. Vertebroplasty was done for 40 patients and kyphoplasty was done for 9 patients with routine manners. To assess the degree of postural reduction, vertebral wedge angles (VWA) and vertebral height ratios (VHR) were calculated by using preoperative StLRs, PrLRs, and postoperative lateral radiographs. Two variables derived from changes in VWA and VHR between preoperative and postoperative radiographs were compared by a paired t-test. Results: The average NRS scores were 6.23 ± 1.67 in StLRs and 5.18 ± 1.47 in PrLRs. The degree of pain provocation was lower in using PrLRs than StLRs (p < 0.001). The average changes of VWA between preoperative and postoperative status were 5.24° ± 6.16° with PrLRs and 3.46° ± 3.47° with StLRs. The average changes of VHR were 0.248 ± 0.178 with PrLRs and 0.148 ± 0.161 with StLRs. The comparisons by two variables showed significant differences for both parameters (p = 0.021 and p < 0.001, respectively). The postoperative radiological status was reflected more precisely when using PrLRs than StLRs. Conclusions: In comparison with StLR, the PrLR was more accurate in predicting the degree of restoration of postoperative vertebral heights and wedge angles, and provoked less pain during examination. The PrLR could be a useful diagnostic tool to detect intravertebral cleft or intravertebral dynamic instability.OAIID:oai:osos.snu.ac.kr:snu2013-01/102/0000004226/12ADJUST_YN:YEMP_ID:A079510DEPT_CD:801FILENAME:clin orthop surg-2013_cho_usefulness of prone cross-table lateral radiographs in vertebral compression fractures.pdfDEPT_NM:의학과CONFIRM:

Prognosis of Single Spinal Metastatic Tumors: Predictive Value of the Spinal Instability Neoplastic Score System for Spinal Adverse Events

Study Design This was a retrospective cohort study. Purpose We evaluated the predictive value of the Spinal Instability Neoplastic Score (SINS) system for spinal adverse events (SAEs) in patients with single spinal metastatic tumor. Overview of Literature The SINS system was developed to assess spinal instability in patients with single metastatic spinal tumor. However, the system’s potential predictive value for SAEs has been partially studied. Methods This system was applied to a retrospective cohort of 78 patients with single spinal metastatic tumors. The patients underwent surgical treatment and were postoperatively followed up for at least 2 years or until death. The attribution of each score and total SINS to SAE (vertebral compression fracture [VCF] and spinal cord compression [SCC]) occurrence was assessed using the Cox proportional hazards model. Results SAEs occurred on average 7 months after diagnosis of spinal metastasis. The mean survival rate post diagnosis was 43 months. Multivariate analysis using the Cox proportional hazards model revealed that the pain (p=0.029) and spinal alignment (p=0.001) scores were significantly related to VCF occurrence, whereas the pain (p=0.008) and posterolateral involvement (p=0.009) scores were related to SCC occurrence. Conclusions Among the components of the SINS system, while pain and spinal alignment showed a significant association with VCF occurrence, pain and posterolateral involvement showed association with SCC occurrence