The Misspecification of Components and Factors

Factor and component analysis are two similar statistical procedures widely-used to reduce a set of p variables to a smaller set of m variables. This reduced set of m components or factors can be interpreted as an overall pattern structure or used in the derivation of factor and component scores. A commonly occurring and potentially serious problem concerns the misspecification of the number of factors and components (m). Misspecifications can take the form of extracting too many or too few factors or components. A series of simulation studies was undertaken to determine the practical effects of such misspecifications within and between the methods of maximum likelihood factor analysis (MLFA) and principal component analysis (PCA). Computer-simulated data sets, representing baseline factor and component patterns, were generated to represent a wide range of conditions. Item saturation, (aij - .4, .6 & .8), sample size (N - 75, 150, 225 & 450), and the variable to component and factor ratios (p:m - 4:1, 6:1 & 12:1) were systematically varied to create the baseline patterns prior to deliberate misspecifications. The problem was examined from several perspectives by investigating relationships within MLFA and PCA during both overextraction and underextraction, and by investigating relationships between MLFA and PCA during overextraction, underextraction and for the correct structural patterns. Results indicated an overall degradation in the MLFA and PCA solutions during both overextraction and underextraction. Although degradation within methods occurred during overextraction, little information was lost even at maximal overextraction for the strongest (aij = .8 & .6) pattern structures during either MLFA or PCA. By contrast, underextraction was a very serious problem with much loss of information occurring at the first underextraction and continuing with each successive underextraction. Greater degradation occurred with MLFA than PCA during underextraction. High similarity between MLFA and PCA solutions occurred for the correct pattern specifications and for the overextracted solutions. Low similarity between MLFA and PCA solutions occurred during underextraction. Item saturation was the major determinant, while sample size and variable to component (factor) ratio were lesser though important determinants, of stable pattern structures during overextraction and for correct solutions, both within and between methods. No condition of interest was found to be a consistent determiner of stable pattern structures during underextraction

Business Travels and Cold War mobilities

The article focuses on business travels and introduces a special issue on Business trips and Cold War mobilities. It underlines the relevance of the topic for both the new field of mobility history and the history of mobility under communist regimes during the Cold War

Risk-based evaluation for underground mine planning

As underground mine planning tools become more sophisticated, mine planners have the capacity to investigate numerous mine sequencing options to identify the best strategy for a given project, creating higher value for shareholders. The information required for mine planning decisions goes beyond the external sources of uncertainty recognised by typical evaluation techniques used in the mining industry, to include technical factors (e.g. mine development layout) and the ability of a mineral extraction project to achieve planned production levels. Due to the individual characteristics that define underground mining projects, each will exhibit its individual risk profile, and thus advanced evaluation techniques must capture this information.This paper describes a Risk‐based Evaluation Methodology that accounts for financial and technical scheduling risk in the evaluation of underground mining projects. It provides decision‐makers with more information early in the mine planning cycle by combining planning and design methodologies with evaluation techniques to identify, optimise and evaluate strategies for mining extraction sequences. Standard evaluation practices used in the mining industry (Discounted Cash Flow, Real Options and Monte Carlo Simulation) are combined with the concepts of Modern Portfolio Theory to establish an evaluation methodology that recognises financial uncertainty in the context of technical scheduling factors. This paper will show that the Risk‐based Evaluation Methodology can be used at the tactical level, as it is applied in combination with the Schedule Optimisation Tool (SOT), for the purpose of recommending a materials handling system to be implemented in a mining project. For the case study, the inclusion of more information in the decision‐making process not only provides a more accurate valuation and allows for the recognition of risk, but it also alters the ultimate decision

Digital and sustainable innovation policies in Europe: comparative lessons

The article is the editorial of a special issue of "Innovation. The European Journal for Social Science Research" which deals with digital and sustainable innovations

Use of functional imaging across clinical phases in CNS drug development

The use of novel brain biomarkers using nuclear magnetic resonance imaging holds potential of making central nervous system (CNS) drug development more efficient. By evaluating changes in brain function in the disease state or drug effects on brain function, the technology opens up the possibility of obtaining objective data on drug effects in the living awake brain. By providing objective data, imaging may improve the probability of success of identifying useful drugs to treat CNS diseases across all clinical phases (I–IV) of drug development. The evolution of functional imaging and the promise it holds to contribute to drug development will require the development of standards (including good imaging practice), but, if well integrated into drug development, functional imaging can define markers of CNS penetration, drug dosing and target engagement (even for drugs that are not amenable to positron emission tomography imaging) in phase I; differentiate objective measures of efficacy and side effects and responders vs non-responders in phase II, evaluate differences between placebo and drug in phase III trials and provide insights into disease modification in phase IV trials

Feeding behaviour of dairy cows in forced or free cow traffic in Automatic Milking System (AMS)

AbstractSeveral options have been suggested in the literature for "inviting" the lactating cows to a milking unit, minimizing the interference with the activities of the cows during the day (eating, drinking, resting) and optimizing the welfare of the animals. The aim of this research was to evaluate the effects of forced and free cow traffic on feeding behaviour in primiparous (PR) and pluriparous (PL) cows. The trial was carried out in the experimental free stall barn "V. Tadini" equipped with a single box automatic milking system (Galaxy, Milkline) and with a 40 lactating cows group. Cows were fed once a day (at 07:30 a.m.) the same Total Mixed Ration (TMR). During the trial two different cow traffic situations combined with different feeds management were tested. In the 1st period forced cow traffic (FC) was used; in the 2nd period free cow traffic (FR) but with an increase of the concentrate fed in the milking unit (+1.5 kg/head/day) and a reduction of the concentrate percentage in TMR (from 44.5 to ..

Scenario evaluation through Mine Schedule Optimisation

The Schedule Optimisation Tool (SOT) is a software that identifies the sequence (schedule) of mine development and the ore production activities that maximise the Net Present Value (NPV). A case study exercise in a live mine planning process found that SOT added over a hundred million dollars of value to the orebody. SOT has been enhanced to allow automated generation and evaluation of mine design parameters. The first enhancement allows the automated evaluation of schedules over a range of operational resource constraints. Heuristics can be used to seed the starting point of the search; for example, by prioritising production from specific stopes based on their mineral grades. The second enhancement allows a user‐specified ranking to be applied as a seeding heuristic. A third enhancement allows automated application of sequencing rules for primary and secondary stopes. SOT provides substantial assistance to the mine planner, allowing for strategic decisions based on a thorough evaluation of mine design parameters