ESTIMATION OF ATTRIBUTE IMPORTANCE BY CHOICE TIME IN A RANKING TASK

The evaluation of the quality of products and services as a function of their attributes has been broadly implemented in marketing research. The current methods for identifying important attributes and prioritize them suffer from theoretical and practical limitations. The former are related to the choice of the most appropriate model for the specific experimental context, the latter are due to the large amount of variables (cognitive, context and survey variables) affecting the chosen model. This work aims at presenting a new method for capturing consumer attribute preferences and estimating the relative importance weights by using the choice time in a ranking task. All is made through an e…

<p class="Body"><strong>Biological parameters of <em>Neoseiulus longilaterus</em> (Athias-Henriot) (Parasitiformes, Phytoseiidae) fed on prey and pollen in laboratory conditions</strong></p>

Tetranychus urticae is the most important pest on different crops worldwide. Search for endemic phytoseiid mites co-occurring with the above pest, which might be good candidates as biocontrol agents, represents the policy followed by most scientists in recent years. The aim of the present work was to assess the various biological and demographic parameters of Neoseiulus longilaterus, associated with T. urticae on weeds, in laboratory conditions using the latter tetranychid and pollen of Oxalis pes-caprae as food. The results showed a better performance of the predator on the prey as regards the postembryonic development (7.63 and 8.18 days for prey and pollen respectively) and the demograph…

Valutazione di un bene o servizio attraverso la Conjoint Analysis: un procedimento per modelli non additivi e relative esperienze empiriche

A heuristic method for estimating attribute importance by measuring choice time in a ranking task

The evaluation of a product or service in terms of its attributes has been broadly studied in marketing, management and decision sciences. However, methods for finding important attributes have theoretical and practical limitations. The former are related to the selection of the most appropriate model; the latter are due to large number of variables that affect the specific experimental context. This study aims to present a new methodology that captures attribute preferences from a respondent and in particular, by using the choice time in a ranking task, it allows to indirectly obtain the importance weights for several tested attributes through a simple, fast and inexpensive procedure. More…

Construction and optimality of a special class of balanced designs

The use of balanced designs is generally advisable in experimental practice. In technological experiments, balanced designs optimize the exploitation of experimental resources, whereas in marketing research experiments they avoid erroneous conclusions caused by the misinterpretation of interviewed customers. In general, the balancing property assures the minimum variance of first-order effect estimates. In this work the authors consider situations in which all factors are categorical and minimum run size is required. In a symmetrical case, it is often possible to find an economical balanced design by means of algebraic methods. Conversely, in an asymmetrical case algebraic methods lead to e…

Rethinking the risk matrix

So far risk has been mostly defined as the expected value of a loss, mathematically PL (being P the probability of an adverse event and L the loss incurred as a consequence of the adverse event). The so called risk matrix follows from such definition. This definition of risk is justified in a long term “managerial” perspective, in which it is conceivable to distribute the effects of an adverse event on a large number of subjects or a large number of recurrences. In other words, this definition is mostly justified on frequentist terms. Moreover, according to this definition, in two extreme situations (high-probability/low-consequence and low-probability/high-consequence), the estimated risk…

Design and analysis of discrete choice experiments for models with response time

Effectiveness of spinosad and mineral oil for control of Grapholita funebrana Treitschke in organic plum orchards

An experiment was conducted in an organic plum orchard in Sicily to evaluate the damage caused by the plum moth Grapholita funebrana (Treitschke) to three plum cultivars (Angeleno, Friar, and Stanley) and to evaluate plum moth control provided by mineral oil applied every 20 days (Moil), spinosad applied every 10 days (S10), or spinosad and mineral oil applied alternately (S/Moil). Treatment application began when eggs were first observed on fruits. S10 and S/Moil effectively reduced plum moth damage on all cultivars but Moil did not. Plum moth infestation was significantly lower on Stanley than on Friar and Angeleno.

Do Grapholita funebrana Infestation Rely on Specific Plum Fruit Features?

The effective control of the plum fruit moth, Grapholita funebrana (Lepidoptera: Tortricidae) still represents a difficult challenge for organic plum farming. Little information is available on the susceptibility of plum cultivars to this moth pest. We investigated the roles of several fruit parameters (i.e., shape, volume, hardness, fruit colour, and physiochemical properties) on the susceptibility of four different plum cultivars (Angeleno, Friar, President and Stanley) to G. funebrana attack. Field data demonstrated the importance of some fruit parameters (i.e., elongation index, sugar degree, titratable acidity, cover colour percentage) on susceptibility to G. funebrana infestation. Und…

Relation of fruit color, elongation, hardness, and volume to the infestation of olive cultivars by the olive fruit fly, Bactrocera oleae

The susceptibility of olive cultivars to the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), has seldom been studied. This article examines factors associated with olive fruit fly infestation of 16 commonly planted Sicilian olive cultivars. Total infestation data were simultaneously correlated with categorical and quantitative factors using ordinal logistic regression. When all factors were included in the analysis, year, sampling date, cultivar, and fruit color were highly significant, but the quantitative factors fruit volume, fruit elongation, and fruit hardness were not. When the analysis was repeated excluding cultivar, all quantitative factors were significant, and e…

On the perception of leaf morphology and visible light by Tetranychus urticae Koch (Acariformes, Tetranychidae)

The two-spotted spider mite Tetranychus urticae is one of the most polyphagous and most damaging pests worldwide. The behaviour of the mite differs on its various host plants and this could influence crop defence strategies. We investigated the perception of leaf morphology by T. urticae in relation to the effects of visible light on the selection of sites on which females prefer to live and feed. Mite females chose the shaded surface when smooth and glabrous lemon leaves were offered as a surface for living and feeding, showing a photophobic behaviour. However, they clearly preferred the abaxial surface of bean leaves regardless of the presence or absence of visible light. As no difference…

FACTORS AFFECTING THE INFESTATION DUE TO BACTROCERA OLEAE (ROSSI) IN SEVERAL SICILIAN OLIVE CULTIVARS

A non-homogeneous Poisson based model for daily rainfall data

In this paper we report some results of the application of a new stochastic model applied to rainfall daily data. The Poisson models, characterized only by the expected rate of events (impulse occurrences, that is the mean number of impulses per unit time) and the assigned probability distribution of the phenomenon magnitude, do not take into consideration the datum regarding the duration of the occurrences, that is fundamental from a hydrological point of view. In order to describe the phenomenon in a way more adherent to its physical nature, we propose a new model simple and manageable. This model takes into account another random variable, representing the duration of the rainfall due to…

A Comparison of Two Classes of Nearly Orthogonal Designs

Prioritization of the balancing property and full estimability in mixed-level designs

In a recently published work, a new class of Balanced Asymmetrical Nearly Orthogonal Designs (BANOD2) was proposed, which can simultaneously estimate both first and second order effects of all factors, with a limited run size. The motivation for the new class lies in using the balancing property as a necessary precondition for several practical concerns arising in the experimentation field. A balanced design optimizes the use of experimental resources in technological experiments, may avoid misinterpretations in choice experiments of marketing research, and can relieve the experimenter from the arbitrariness in assigning the levels to factors. Furthermore the balancing property assures the …

Biological and life table parameters of Typhlodromus laurentii and Iphiseius degenerans (Acari, Phytoseiidae) fed on Panonychus citri and pollen of Oxalis pes-caprae under laboratory conditions

Typhlodromus laurentii and Iphiseius degenerans are two generalist phytoseiid mites, broadly spread in the Mediterranean area, especially in citrus orchards. In the present work we report results on various biological and life table parameters of the two phytoseiids, fed on pollen of Oxalis pes-caprae and various stages of the tetranychid Panonychus citri. Iphiseius degenerans had the shortest post embryonic development (6.53 days), the highest oviposition rate (1.83 eggs/female/day) and the shortest mean time between eggs laid (0.55 day) on Oxalis pollen, whereas the two food types did not influence these parameters in T. laurentii. However, Oxalis pollen showed a positive effect on the su…

Tool replacement with adaptive control in a non-stationary non-periodic stochastic process

Abstract The problem of optimum tool replacement is studied in the case in which tool performance is characterized by progressive decay over time following stochastic laws. A control system is assumed which detects, continuously or at fixed intervals, the service state of the tool. Assuming that the service state of the tool affects the marginal cost of production, the latter is used in order to minimize the unit production cost for an unlimited production horizon. The replacement policy proposed is able to update itself in process by means of an iterative procedure which converges to a conditioned optimum. The effectiveness of such a policy is demonstrated analytically, and illustrative ex…

EFFECTIVENESS OF SPINOSAD AND MINERAL OIL BASED COMMERCIAL PRODUCTS ON OVIPOSITION AND EGG HATCHING OF GRAPHOLITA FUNEBRANA TREITSCHKE

Laboratory trials were performed to evaluate the action of spinosad and mineral oil on eggs of Grapholita funebrana Treitschke, the key pest in plum orchards. Fruits of cultivars Angeleno, President and Stanley were used in the trials. The first set of tests was carried out by introducing two mated females of G. funebrana into a cage together with fruits of a single cultivar. The second set of trials tested the three cultivars simultaneously. In all trials, one third of the fruits of each cultivar was treated with mineral oil, another third with spinosad and the final third was left untreated. Treatments were carried out before introducing mated females into the cages. The number of fruits …

Prioritization of Alternatives with AHP Plus Response Latency and Web Surveys

Purpose: Overcome some drawbacks of the widely applied Analytical Hierarchy Process (AHP) related to the use of a rating scale for respondent’s judgments and propose a new method to prioritize alternatives based on web surveys. Methodology/Approach: We use the response latency, i.e. the time taken to make a decision, to replace the rating scale in the pairwise comparisons which is a fundamental part of the AHP procedure. A method combining the AHP with a mathematical model for the response latency is proposed in the paper. Findings: Eliminating the rating scale and leaving only the “take the best” task alleviates the respondent and makes the survey much faster and intuitive. Moreover the re…

Implementation of Six Sigma in SMEs. A Case Study in Swedish Industry

Many big companies today have already solid Six Sigma infrastructures. However, all over the world SMEs are only now approaching the methodology. In this presentation we expose an industrial application of a Six Sigma Black Belt project. It shows how Six Sigma was introduced and successfully implemented in a Swedish small-medium sized company. The project was carried out within the Six Sigma Black Belt course run at Chalmers University of Technology in Gothenburg. This case study is included in the book “Statistical and Managerial Techniques for Six Sigma Methodology, Theory and Application” (Wiley, 2012). The company is Structo Hydraulics AB, a manufacturing firm, located in Storfors, whic…

ENVIRONMENTAL FACTORS IMPACT AND INCIDENCE OF PARASITISM OF PSYLLAEPHAGUS BLITEUS RIEK (HYMENOPTERA ENCYRTIDAE) ON POPULATIONS OF GLYCASPIS BRIMBLECOMBEI MOORE (HEMIPTERA APHALARIDAE) IN MEDITERRANEAN CLIMATIC AREAS

The red gum lerp psyllid, Glycaspis brimblecombei Moore (Hemiptera, Aphalaridae), is an Australian native sap-sucking insect pest of eucalypts that has been first reported for the West Palaearctic Region in 2008 and, in 2010, it has been found also in Italy. Subsequently its primary parasitoid, Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae), was also detected within the main European and North African infested areas, where no release of the parasitoid was ever performed. This study, carried out in 30 Eucalyptus camaldulensis plantations located along the coast, on the hills and the mountains in Mediterranean climatic areas of Sicily (Italy), aimed to determine the influence of environ…

A tool for generating new optimal designs in conjoint analysis experiments

Valutazione della soddisfazione mediante Adaptive Conjoint Analysis con dati metrici e non metrici: un’applicazione al servizio universitario messinese

A weighted logistic regression for conjoint analysis and Kansei engineering

Customer needs for emotional satisfaction are increasingly being considered by product and service designers. While several existing methods such as conjoint analysis (CA), Kano model and quality function deployment support the translation of customer requirements into technical specifications, researchers are now working to develop methods aimed at integrating affective aspects into product design. Kansei engineering (KE) is a design philosophy that considers customer perceptions and emotions by adopting a multi-disciplinary approach. CA is a useful tool within a KE project. This article presents a methodology for conducting a KE project in early development phases. This methodology is bas…

Balanced Asymmetrical Nearly Orthogonal Designs for first and second order effect estimation

Abstract A method for constructing asymmetrical (mixed-level) designs, satisfying the balancing and interaction estimability requirements with a number of runs as small as possible, is proposed in this paper. The method, based on a heuristic procedure, uses a new optimality criterion formulated here. The proposed method demonstrates efficiency in terms of searching time and optimality of the attained designs. A complete collection of such asymmetrical designs with two- and three-level factors is available. A technological application is also presented.

The role of thermal contribution in the design of AA2024 friction stir welded butt and lap joints: mechanical properties and energy demand

Although in recent times the use of solid-state welding processes as friction stir welding (FSW) has become increasingly widespread, for some joint morphologies, as lap joints, there are still signifcantly less data available on both process parameters optimization and energy consumption. In the present paper, the authors investigated the possibility of enhancing the joint quality in two diferent confgurations, i.e. lap and butt joints, taking into account specifc thermal contribution (STC) conferred to the weld. Strength, micro-hardness and microstructure were evaluated on the produced AA2024 aluminum alloys butt and lap joints. The surface response method (RSM) was used to investigate the…

Effects of Kaolin on Ophelimus maskelli (Hymenoptera: Eulophidae) in Laboratory and Nursery Experiments

Although recent research has demonstrated that clays provide satisfactory control of some agricultural insect pests, the effect of clays on gall wasps that damage forest trees has not been previously reported. The aim of the current study is to evaluate the effectiveness of the clay kaolin in the laboratory and in the field in reducing the damage caused by the eulophid Ophelimus maskelli (Ashmead) on seedlings of eucalyptus (Eucalyptus L'Hér.) species. In the laboratory, kaolin + wetting agent significantly reduced the percentage of infested leaves and the number of galls per leaf. In the nursery, gall number per leaf was not correlated with leaf area with kaolin + wetting agent but was rel…

Service Quality design through a smart use of Conjoint Analysis

Analysis of User Needs for the Redesign of a Postural Seat System

The identification and translation of customer needs early in the design process is a major challenge for product design researchers. Some needs are explicit and customers can state them very clearly. Other needs are implicit, so customers cannot express them, e.g., those pertaining to the affective and emotional sphere. In this work, we describe the methods most commonly used to capture explicit and emotional customer needs, and the traditional ways in which they are used. Moreover, an integration of QFD and Kansei engineering, a simplification of Kano methodology, and a new attribute weighing methodology based on the “choice time” are discussed for the design of an innovative postural sea…

Analysis of user needs for the re-design of a wheelchair

The identification and translation of customer needs early in the design process is a major challenge for product design researchers. Some needs are explicit and customers can state them very clearly. Other needs are implicit, so customers cannot express them, e.g., those pertaining to the affective and emotional sphere. In this work, we describe the methods most commonly used to capture explicit and emotional customer needs, and the traditional ways in which they are used. Moreover, an integration of QFD and Kansei engineering, a simplification of Kano methodology, and a new attribute weighing methodology based on the “choice time” are discussed for the design of an innovative postural sea…

A predictive maintenance policy with imperfect monitoring

For many systems,failure is a very dangerous or costly event. To reduce the occurrence of this event,it is necessary to implement a preventive maintenance policy to replace the critical elements before failure.Since elements do not often exhibit incipient faults, they are replaced before a complete exploiting of their useful life.To conjugate the objective of exploiting elements for almost all their useful life with the objective to avoid failure,condition based and,more recently,predictive maintenance policies have been proposed.This paper deals with this topic and proposes a procedure for the computation of the maintenance time that minimizes the global maintenance cost.By adopting a stoc…

Enhanced multinomial logit model for the analysis of choice experiments

A sector of conjoint analysis (experimental design in marketing research) is made of the so called choice experiments. In choice experiments respondents undergo a questionnaire which is nowadays mostly submitted through the internet. The questionnaire proposes to the respondent a sequence of choice sets each one including two or more profiles, being a profile a specific combination of attribute levels. The respondent selects the preferred profile for each choice set. Responses given by a sample of respondents are analysed through suitable methods aimed to eventually find the best combination of attribute levels. One method of analysis adopts the Multinomial Logit (MLN) model. In this articl…

Plant structure as a determinant of coriander (Coriandrum sativum L.) seed and straw yield

Abstract Coriander (Coriandrum sativum L., Apiaceae) is a Mediterranean aromatic plant that is mainly cultivated for its fruits. Understanding the association between various vegetative and reproductive structures as they pertain to yield can help addressing efforts for achieving the highest productivity levels, by improving both cropping techniques and breeding. Multiple Regression (MR) analysis is a suitable tool to understand this association; notwithstanding, due to the plant’s inherent “weedy” growth, the interpretation of MR results in coriander is often difficult. Therefore, in our analysis we also calculated additional indicators of variable contribution to the model and to one anot…

Study of bubble size distribution in bubbling fluidized beds via Digital Image Analysis Technique

Six Sigma in small- and medium-sized enterprises: a Black Belt project in the Swedish steel industry

Many big companies around the world have solid Six Sigma infrastructures and it is easy to find in literature successful case studies. Conversely, small and medium-sized enterprises (SMEs) generally suffer lower attention in the literature. This happens because SMEs have only recently approached the methodology; they have weaker connection with the academia; or they do not rigorously pursue the frameworks. This paper is based on a Six Sigma project in a Swedish medium-sized company that produces steel tubes mainly for hydraulic applications. The project focused on the improvement of warehouse activities related to cutting processes. This Black Belt project was part of a Six Sigma education …

Influenza dell’altitudine e di due tecniche agronomiche sull’infestazione e i danni indiretti causati da Lobesia botrana (denis et Schiffermüller) (Lepidoptera, tortricidae)

Two years (2008-2009) field observations were carried out to evaluate the effects of altitude, of kaolin application and of early leaf thinning practice on the infestation level and damages caused by grape moth Lobesia botrana. The difference of 80 m. a.s.l. significantly influenced the infestation level of grape moth, which was lower, of about 20%, at the higher altitude. The early leaf thinning practice did not influence the grape moth infestation nor the presence of sour bunch rot and grey mould on grapes. On the other hand, kaolin sprayings significantly reduced the infestation level in both altitudes (from 11 to 22%) as well as the presence of sour bunch rot and fungi. However, the per…

Prioritisation of alternatives with analytical hierarchy process plus response latency and web surveys

This paper introduces a new method that combines the well-known analytical hierarchy process (AHP) with a response latency metric. The response latency is the time taken by respondents to make choices over pairwise comparisons. The analytical calculation of relative importance weights of the alternatives is made by using a response latency model previously validated in several case studies. This combination aims to overcome some drawbacks of the traditional AHP related to the use of a rating scale (the so-called Saaty scale), and it is a natural way to involve response latency in established decisionmaking methods. This new method can be profitably adopted in web surveys where it is easy to…

Influence of Distance from the Host on Parasitisation by Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae)

The olive fruit fly, Bactrocera oleae, is considered the main olive pest worldwide, and has been the target of biological control programmes through the release of the braconid parasitoid Psyttalia concolor. Laboratory tests were performed to evaluate the influence of distance from the host on parasitisation, placing larvae of the substitute host Ceratitis capitata at seven distances (0, 0.5, 1, 1.5, 2, 2.5, 3 mm) and four different time periods (7, 15, 30, 60 min). Moreover, field collected olives of Ogliarola Barese cultivar infested by B. oleae were exposed to P. concolor females to confirm its ability to parasitise B. oleae in small olives. Psyttalia concolor oviposition was inhibited a…

Manager’s and citizen’s perspective of positive and negative risks for small probabilities

So far „risk‟ has been mostly defined as the expected value of a loss, mathematically PL, being P the probability of an adverse event and L the loss incurred as a consequence of the event. The so called risk matrix is based on this definition. Also for favorable events one usually refers to the expected gain PG, being G the gain incurred as a consequence of the positive event. These “measures” are generally violated in practice. The case of insurances (on the side of losses, negative risk) and the case of lotteries (on the side of gains, positive risk) are the most obvious. In these cases a single person is available to pay a higher price than that stated by the mathematical expected valu…

Project Management Information Systems (PMISs): A Statistical-Based Analysis for the Evaluation of Software Packages Features

Project Managers (PMs) working in competitive markets are finding Project Management Information Systems (PMISs) useful for planning, organizing and controlling projects of varying complexity. A wide variety of PMIS software is available, suitable for projects differing in scope and user needs. This paper identifies the most useful features found in PMISs. An extensive literature review and analysis of commercial software is made to identify the main features of PMISs. Afterwards, the list is reduced by a panel of project management experts, and a statistical analysis is performed on data acquired by means of two different surveys. The relative importance of listed features is properly comp…