Willingness to Pay for Traceable Meat Attributes: A Meta-analysis

Several researches evaluated consumers’ Willingness To Pay (WTP) for each meat traceable attribute, generating a great deal of information in this regard, although specific to the conditions of each study. In light of this, WTP estimates for traceability characteristics differ across the literature, leading sometimes to contrasting interpretations. Seeking a full, meaningful statistical description of the findings of a collection of studies, the meta-analysis allows us to analyze consistency across studies and control for factors thought to drive variations in WTP estimates. The meta-analysis has been conducted using 23 studies that, in aggregate, report 88 valuations for WTP. Our results, aside from releasing unconditional information on the WTP for single meat traceable attributes, show how certain study-specific characteristics, like the base price and the country where the study has been conducted, have a significant impact on WTP estimatesMeta-analysis, food traceability, Willingness to Pay, Agribusiness, Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Institutional and Behavioral Economics, Production Economics, Research Methods/ Statistical Methods, Risk and Uncertainty,

Empirical Studies On The Effectiveness Of Soda Taxes To Curb Obesity

This dissertation presents a series of empirical studies to evaluate the effectiveness of soda taxes to curb the obesity epidemic. Chapter 1 describes the extent and severity of the obesity problem in the U.S., and discusses the policy interventions that have been proposed or enacted with the intent to fight obesity (e.g., sales taxes). Chapter 2 contains a study on the effect of two tax events on soda consumption: a 5.5% sales tax on soft drinks imposed in Maine in 1991, and a 5% sales tax on soft drinks levied in Ohio in 2003. We investigate this question by using sales data collected by scanner devices in Maine, Massachusetts, New York and Connecticut, as well as Ohio, Illinois, Michigan and Pennsylvania. Results suggest that these sales taxes had a statistically insignificant impact on the overall consumption of soft drinks. Chapter 3 describes an empirical study that looks at whether the 5% sales tax on soft drinks in Ohio in 2003 had a differential impact on different socio-economic segments of the population. In line with the results described in Chapter 2, this study suggests that the impact of a tax had a homogeneous effect (and statistically insignificant) across different demographic groups. In Chapter 4 we investigate whether the demand for soda varies with the obesity rate. To this end we develop a demand model that is able to incorporate dynamic properties of this market as well as the resulting possibility that the obesity rate might alter the parameters of the model

LEVERAGING PROGNOSTIC BASELINE VARIABLES TO GAIN PRECISION IN RANDOMIZED TRIALS

We focus on estimating the average treatment effect in a randomized trial. If baseline variables are correlated with the outcome, then appropriately adjusting for these variables can improve precision. An example is the analysis of covariance (ANCOVA) estimator, which applies when the outcome is continuous, the quantity of interest is the difference in mean outcomes comparing treatment versus control, and a linear model with only main effects is used. ANCOVA is guaranteed to be at least as precise as the standard unadjusted estimator, asymptotically, under no parametric model assumptions, and also is locally, semiparametric efficient. Recently, several estimators have been developed that extend these desirable properties to more general settings that allow: any real-valued outcome (e.g., binary or count), contrasts other than the difference in mean outcomes (such as the relative risk), and estimators based on a large class of generalized linear models (including logistic regression). To the best of our knowledge, we give the first simulation study in the context of randomized trials that compares these estimators. Furthermore, our simulations are not based on parametric models; instead, our simulations are based on resampling data from completed randomized trials in stroke and HIV in order to assess estimator performance in realistic scenarios. We provide practical guidance on when these estimators are likely to provide substantial precision gains, and describe a quick assessment method that allows clinical investigators to determine whether these estimators could be useful in their specific trial contexts

Community Supported Agriculture in the urban fringe: empirical evidence for project potentiality in the metropolitan area of Naples (Italy)

Urbanisation of city-side areas effects on farm land use and organisation are analysed in this study with the objective of seeking the most effective way to implement a Community Supported Agriculture (CSA) scheme. Specifically, we used a theoretical framework to describe and assess the relationships between urbanisation and changes in farm-styles in the city belt. Our analysis is based on a case study in the protected area of the Campi Flegrei Regional Park situated in the north-western part of the Neapolitan metropolitan area, which is a peri-urban rural area with severe environmental management problems. Our results from the empirical analysis allowed us to distinguish the farms of the area into three behavioural-social groups on the basis of specific features, in order to identify the best suited type of farm for the strategic implementation of the CSA. A market scenario was predicted for each of them without any intervention

WTP for Traceable Meat Attributes: A Meta‐analysis

Several researches evaluated consumers’ Willingness To Pay (WTP) for each meat traceable attribute, generating a lot of information in this regard, although related to the conditions of each study. In light of this, WTP estimates for traceability characteristics largely differ across the literature, leading sometimes to contrasting interpretations. Seeking a full, meaningful statistical description of the findings of a collection of studies, the meta ‐analysis allows us analyzing the consistency across studies and controlling for factors thought to drive variations in WTP estimates. The meta‐analysis has been conducted of 23 studies that, in aggregate, report 92 valuations for WTP

Willingness to Pay for Traceable Meat Attributes: A Meta-analysis

 Several researches evaluated consumers’ Willingness To Pay (WTP) for each meat traceable attribute, generating a great deal of information in this regard, although specific to the conditions of each study. In light of this, WTP estimates for traceability characteristics differ across the literature, leading sometimes to contrasting interpretations. Seeking a full, meaningful statistical description of the findings of a collection of studies, the meta-analysis allows us to analyze consistency across studies and control for factors thought to drive variations in WTP estimates. The meta-analysis has been conducted using 23 studies that, in aggregate, report 88 valuations for WTP. Our results, aside from releasing unconditional information on the WTP for single meat traceable attributes, show how certain study-specific characteristics, like the base price and the country where the study has been conducted, have a significant impact on WTP estimates

ENHANCED PRECISION IN THE ANALYSIS OF RANDOMIZED TRIALS WITH ORDINAL OUTCOMES

We present a general method for estimating the effect of a treatment on an ordinal outcome in randomized trials. The method is robust in that it does not rely on the proportional odds assumption. Our estimator leverages information in prognostic baseline variables, and has all of the following properties: (i) it is consistent; (ii) it is locally efficient; (iii) it is guaranteed to match or improve the precision of the standard, unadjusted estimator. To the best of our knowledge, this is the first estimator of the causal relation between a treatment and an ordinal outcome to satisfy these properties. We demonstrate the estimator in simulations based on resampling from a completed randomized clinical trial of a new treatment for stroke; we show potential gains of up to 39\% in relative efficiency compared to the unadjusted estimator. The proposed estimator could be a useful tool for analyzing randomized trials with ordinal outcomes, since existing methods either rely on model assumptions that are untenable in many practical applications, or lack the efficiency properties of the proposed estimator. We provide R code implementing the estimator

ROBUST ESTIMATION OF THE AVERAGE TREATMENT EFFECT IN ALZHEIMER\u27S DISEASE CLINICAL TRIALS

The primary analysis of Alzheimer\u27s disease clinical trials often involves a mixed-model repeated measure (MMRM) approach. We consider another estimator of the average treatment effect, called targeted minimum loss based estimation (TMLE). This estimator is more robust to violations of assumptions about missing data than MMRM. We compare TMLE versus MMRM by analyzing data from a completed Alzheimer\u27s disease trial data set and by simulation studies. The simulations involved different missing data distributions, where loss to followup at a given visit could depend on baseline variables, treatment assignment, and the outcome measured at previous visits. The TMLE generally has improved robustness in our simulated settings, i.e., less bias and mean squared error, and better confidence interval coverage probability. The robustness is due to the TMLE correctly modeling the dropout distribution. We illustrate the tradeoffs between these estimators and give recommendations for how to use these estimators in practice

Feed-food and land use competition of lowland and mountain dairy cow farms

Dairy cows and other ruminants contribute to human nutrition as they are able to convert feed components containing human inedible fibre concentrations (e.g. roughage and by-products from the food processing industry) into valuable animal-sourced food. A number of crops often fed to dairy cows (e.g. soy or cereals) are however potentially edible by humans too. Additionally, land used to grow dairy cattle feed on may compete with crop production for human consumption. Two different methods to assess the competition between feed consumption of dairy cows and human food supply were thus refined and tested on 25 Swiss dairy farms. With respect to the potential human edibility of the feeds used in dairy production, the human edible feed conversion ratio (eFCR) was applied. The land use ratio (LUR) was used to relate the food production potential, per area of land utilized, with the dairy production output. Low to medium eFCR, with values ranging from 0.02 to 0.68 were found, as an average proportion of 0.74 of total DM intake consisted of roughage. In contrast, we found relatively high LUR (0.69 to 5.93) for most farms. If the land area used to produce feed for cows was used for crop production (applying a crop rotation), 23 of the 25 farms could have produced more edible protein and all farms more human edible energy. Indicator values strongly depend on the underlying scenarios, such as the human edible proportion of feeds or the suitability of land and climate for crop production. Reducing the amount of human edible feeds in dairy farming by feeding by-products from the food processing industry and improving forage quality may be suitable strategies to reduce eFCR, but relying on low-opportunity cost feeds may restrict milk performance level per cow. On farm level, improving overall efficiency and therefore using less land (especially area suitable for crop production) per kg product decreases LUR. However, the most promising strategy to mitigate land use competition may be to localize dairy production to land areas not suitable for crop production. Both methods (eFCR and LUR) should be used in parallel. They offer an opportunity to holistically evaluate the net contribution of dairy production to the human food supply under different environmental conditions and stress the importance of production systems well suited to specific farm site characteristics