Combining propensity and influence models for product adoption prediction

This paper studies the problem of selecting users in an online social network for targeted advertising so as to maximize the adoption of a given product. In previous work, two families of models have been considered to address this problem: direct targeting and network-based targeting. The former approach targets users with the highest propensity to adopt the product, while the latter approach targets users with the highest influence potential – that is users whose adoption is most likely to be followed by subsequent adoptions by peers. This paper proposes a hybrid approach that combines a notion of propensity and a notion of influence into a single utility function. We show that targeting a fixed number of high-utility users results in more adoptions than targeting either highly influential users or users with high propensity.

The accuracy of varietal selection using factor analytic models for multi-environment plant breeding trials

Modeling of cultivar x trial effects for multienvironment trials (METs) within a mixed model framework is now common practice in many plant breeding programs. The factor analytic (FA) model is a parsimonious form used to approximate the fully unstructured form of the genetic variance-covariance matrix in the model for MET data. In this study, we demonstrate that the FA model is generally the model of best fit across a range of data sets taken from early generation trials in a breeding program. In addition, we demonstrate the superiority of the FA model in achieving the most common aim of METs, namely the selection of superior genotypes. Selection is achieved using best linear unbiased predictions (BLUPs) of cultivar effects at each environment, considered either individually or as a weighted average across environments. In practice, empirical BLUPs (E-BLUPs) of cultivar effects must be used instead of BLUPs since variance parameters in the model must be estimated rather than assumed known. While the optimal properties of minimum mean squared error of prediction (MSEP) and maximum correlation between true and predicted effects possessed by BLUPs do not hold for E-BLUPs, a simulation study shows that E-BLUPs perform well in terms of MSEP.

Models for the field-based toxicity of copper and zinc salts to wheat in 11 Australian soils and comparison to laboratory-based models

Laboratory-based relationships that model the phytotoxicity of metals using soil properties have been developed. This paper presents the first field-based phytotoxicity relationships. Wheat(Triticum aestivum L) was grown at 11 Australian field sites at which soil was spiked with copper (Cu) and zinc (Zn) salts. Toxicity was measured as inhibition of plant growth at 8 weeks and grain yield at harvest. The added Cu and Zn EC10 values for both endpoints ranged from approximately 3 to 4760 mg/kg. There were no relationships between field-based 8-week biomass and grain yield toxicity values for either metal. Cu toxicity was best modelled using pH and organic carbon content while Zn toxicity was best modelled using pH and the cation exchange capacity. The best relationships estimated toxicity within a factor of two of measured values. Laboratory-based phytotoxicity relationships could not accurately predict field-based phytotoxicity responses.

Annual forecasting of the Australian macadamia crop - integrating tree census data with statistical climate-adjustment models

To facilitate marketing and export, the Australian macadamia industry requires accurate crop forecasts. Each year, two levels of crop predictions are produced for this industry. The first is an overall longer-term forecast based on tree census data of growers in the Australian Macadamia Society (AMS). This data set currently accounts for around 70% of total production, and is supplemented by our best estimates of non-AMS orchards. Given these total tree numbers, average yields per tree are needed to complete the long-term forecasts. Yields from regional variety trials were initially used, but were found to be consistently higher than the average yields that growers were obtaining. Hence, a statistical model was developed using growers' historical yields, also taken from the AMS database. This model accounted for the effects of tree age, variety, year, region and tree spacing, and explained 65% of the total variation in the yield per tree data. The second level of crop prediction is an annual climate adjustment of these overall long-term estimates, taking into account the expected effects on production of the previous year's climate. This adjustment is based on relative historical yields, measured as the percentage deviance between expected and actual production. The dominant climatic variables are observed temperature, evaporation, solar radiation and modelled water stress. Initially, a number of alternate statistical models showed good agreement within the historical data, with jack-knife cross-validation R2 values of 96% or better. However, forecasts varied quite widely between these alternate models. Exploratory multivariate analyses and nearest-neighbour methods were used to investigate these differences. For 2001-2003, the overall forecasts were in the right direction (when compared with the long-term expected values), but were over-estimates. In 2004 the forecast was well under the observed production, and in 2005 the revised models produced a forecast within 5.1% of the actual production. Over the first five years of forecasting, the absolute deviance for the climate-adjustment models averaged 10.1%, just outside the targeted objective of 10%.

The sensitivity of updated NIR PLS models for fruit sorting to initial parameter settings

Partial least squares regression models on NIR spectra are often optimised (for wavelength range, mathematical pretreatment and outlier elimination) in terms of calibration terms of validation performance with reference to totally independent populations.

How to design educational settings to promote collaborative inquiry: Pedagogical infrastructures for technology-enhanced progressive inquiry

Strategies of scientific, question-driven inquiry are stated to be important cultural practices that should be educated in schools and universities. The present study focuses on investigating multiple efforts to implement a model of Progressive Inquiry and related Web-based tools in primary, secondary and university level education, to develop guidelines for educators in promoting students collaborative inquiry practices with technology. The research consists of four studies. In Study I, the aims were to investigate how a human tutor contributed to the university students collaborative inquiry process through virtual forums, and how the influence of the tutoring activities is demonstrated in the students inquiry discourse. Study II examined an effort to implement technology-enhanced progressive inquiry as a distance working project in a middle school context. Study III examined multiple teachers' methods of organizing progressive inquiry projects in primary and secondary classrooms through a generic analysis framework. In Study IV, a design-based research effort consisting of four consecutive university courses, applying progressive inquiry pedagogy, was retrospectively re-analyzed in order to develop the generic design framework. The results indicate that appropriate teacher support for students collaborative inquiry efforts appears to include interplay between spontaneity and structure. Careful consideration should be given to content mastery, critical working strategies or essential knowledge practices that the inquiry approach is intended to promote. In particular, those elements in students activities should be structured and directed, which are central to the aim of Progressive Inquiry, but which the students do not recognize or demonstrate spontaneously, and which are usually not taken into account in existing pedagogical methods or educational conventions. Such elements are, e.g., productive co-construction activities; sustained engagement in improving produced ideas and explanations; critical reflection of the adopted inquiry practices, and sophisticated use of modern technology for knowledge work. Concerning the scaling-up of inquiry pedagogy, it was concluded that one individual teacher can also apply the principles of Progressive Inquiry in his or her own teaching in many innovative ways, even under various institutional constraints. The developed Pedagogical Infrastructure Framework enabled recognizing and examining some central features and their interplay in the designs of examined inquiry units. The framework may help to recognize and critically evaluate the invisible learning-cultural conventions in various educational settings and can mediate discussions about how to overcome or change them.

A global perspective on psycho-educational assessment

For psychologists in less developed countries, psycho-educational assessment is often challenging due to a lack of specialist training and a scarcity of appropriate, psychometrically robust instruments. This paper focuses on school psychology and psycho-educational assessment in three countries: Bangladesh, China and Iran. Despite differences in demographic and cultural features, these countries share similar issues that restrict the practice of psycho-educational assessment. We conclude that it is important for psychologists in western countries to support professional training and testing practices in less developed countries.

Optimization models for expanding a railway’s theoretical capacity

Changing the topology of a railway network can greatly affect its capacity. Railway networks however can be altered in a multitude of different ways. As each way has significant immediate and long term financial ramifications, it is a difficult task to decide how and where to expand the network. In response some railway capacity expansion models (RCEM) have been developed to help capacity planning activities, and to remove physical bottlenecks in the current railway system. The exact purpose of these models is to decide given a fixed budget, where track duplications and track sub divisions should be made, in order to increase theoretical capacity most. These models are high level and strategic, and this is why increases to the theoretical capacity is concentrated upon. The optimization models have been applied to a case study to demonstrate their application and their worth. The case study evidently shows how automated approaches of this nature could be a formidable alternative to current manual planning techniques and simulation. If the exact effect of track duplications and sub-divisions can be sufficiently approximated, this approach will be very applicable.

Parameter estimation and sensitivity analysis of fat deposition models in beef steers using acslXtreme.

The Davis Growth Model (a dynamic steer growth model encompassing 4 fat deposition models) is currently being used by the phenotypic prediction program of the Cooperative Research Centre (CRC) for Beef Genetic Technologies to predict P8 fat (mm) in beef cattle to assist beef producers meet market specifications. The concepts of cellular hyperplasia and hypertrophy are integral components of the Davis Growth Model. The net synthesis of total body fat (kg) is calculated from the net energy available after accounting tor energy needs for maintenance and protein synthesis. Total body fat (kg) is then partitioned into 4 fat depots (intermuscular, intramuscular, subcutaneous, and visceral). This paper reports on the parameter estimation and sensitivity analysis of the DNA (deoxyribonucleic acid) logistic growth equations and the fat deposition first-order differential equations in the Davis Growth Model using acslXtreme (Hunstville, AL, USA, Xcellon). The DNA and fat deposition parameter coefficients were found to be important determinants of model function; the DNA parameter coefficients with days on feed >100 days and the fat deposition parameter coefficients for all days on feed. The generalized NL2SOL optimization algorithm had the fastest processing time and the minimum number of objective function evaluations when estimating the 4 fat deposition parameter coefficients with 2 observed values (initial and final fat). The subcutaneous fat parameter coefficient did indicate a metabolic difference for frame sizes. The results look promising and the prototype Davis Growth Model has the potential to assist the beef industry meet market specifications.

Monikulttuurisen akateemisen opetuksen hallinta

Starting point for the study was the notion made in previous studies that the Finnish educational practices are not sufficient in multicultural teaching. The main objective of the research was to find out good multicultural teaching practices developed by experienced teachers. The subject of the research was teachers narratives about the problems, solutions and the development of multicultural academic teaching. Previous research has shown that disturbances in multicultural activity can be caused among other things by cultural and linguistic differences, racism and prejudice and stress related to immigration. The management of multicultural teaching can be examined from the individual point of view as intercultural competence and from the collective point of view as management of the disturbances of multicultural teaching. The development of the management has been illustrated with the models of adaptation and transformative/expansive learning. The methodological approach of the research was narrative. I interviewed six teachers with narrative methods. Half of the interviews were pair interviews. As an analytical framework I used the basic story model by Labov (1972). I analysed critical incidents, resolutions and evaluations of the stories. According to the results the problems of the multicultural academic teaching are diverse. Most often mentioned problems were cultural differences and racism. Problems were managed by developing practices that support the multicultural activity broadly and by reacting to sudden problems intuitively or reflectively. In the management of the academic multicultural teaching the experienced teachers emphasised flexibility, group building and trust, intensified guidance, acting against racism and prejudice and characteristics of the teacher, like patience and sense of humour. The management of multicultural teaching has developed through the accumulation of intercultural experiences, reflection of experiences, cooperative problem solving, following the research of the field and experimenting different approaches. In accordance with the previous studies, this research showed that continuous learning is needed in the management of multicultural teaching. The results can be used in developing academic multicultural teaching and education.

Monikulttuurisuuskasvatus päiväkodin monikulttuurisessa esiopetusryhmässä

This study reports on the realisation of multicultural education in a multicultural pre-school group of one kindergarten. The research questions were: 1) what multicultural goals and contents did the kindergarten´s own pre-school curriculum contain? and 2) how did the pre-school educators´ views on multicultural education appear in their actions in a multicultural pre-school group? The research was conducted by analysing the curricula, interviewing the educators, and observing of the preschool groups. Pre-school education is seen as part of institutionalised education which is defined through culture. Education is considered from the point of view of critical multicultural education, paying special attention to the role of society in the definition of education. The research is a case study, and it concentrates on the interpretation of the working philosophy of one preschool group with respect to its implementation. The target group consisted of 20 6-year-old pre-school pupils in a kindergarten and their four pre-school educators. The research results showed that the kindergarten´s own pre-school curriculum (1997) was in structure and form consistent with the structure and form of the National Core Curriculum for Pre-School Education from 1996. The only difference was in the classification of the various subject fields and objectives. The contents of the two curricula showed hardly any variation, and both of them contained only few goals and contents for multicultural education. According to the interviews, the educational views and learning philosophy of the pre-school educators represented a child-centred point of view that takes into consideration the individual pupil´s needs and skills. This is also one of the basic principles of multicultural education. The principle was not, however, realised in the directed activities of the pre-school group. The heterogeneity of the pre-school group was dealt with by dividing the children into smaller groups, but the contents of the tuition were not differentiated. All children were provided with the same goals and contents. Multicultural education was seen as remote and separate from the overall educational philosophy. The contents of multicultural education were interpreted by the educators as teaching Finnish as a second language and teaching the children their own mother tongue and religion. After the evaluation of the state of the kindergarten´s multicultural education using four different models, I determined that the kindergarten emerged as a representative of the model where multicultural education is seen as something meant for immigrants only. The aim of the model is a rapid integration of the immigrant children with the majority population. Keywords: education, pre-school education, multicultural education, critical multicultural education, language, culture