Search results for "Mixture model"
showing 10 items of 86 documents
A longitudinal person-centred approach to the job demands-control model
2016
We used a longitudinal design and a person-centred methodology to test the strain and learning hypotheses of the job demands–control model among Finnish employees (n = 926), who were followed-up at three time points covering a period of 2 years (2008–2010). First, we identified longitudinal subgroups in demands and control across three measurement points. Second, we examined how these subgroups differed in strain (job exhaustion) and motivation-related outcomes (vigour at work, work–family enrichment). Growth mixture modelling revealed four subgroups: “stable high strain”, “stable low strain”, “increasing control”, and “decreasing control”. The stable high- and low-strain subgroups also dif…
Job resources and flow at work : modeling the relationship via latent growth curve and mixture model methodology
2010
The aim of the present three-wave follow-up study (n = 335) among employees of an employment agency was to investigate the association between job resources and work-related flow utilizing both variable- and person-oriented approaches. In addition, emotional exhaustion was studied as a moderator of the job resources-flow relationship, and as a predictor of the development of job resources and flow. The variable-oriented approach, based on latent growth curve analyses, revealed that the levels of job resources and flow at work, as well as changes in these variables, were positively associated with each other. The person-oriented inspection with the growth mixture modelling identified four tr…
Trajectories of change in reading self-efficacy: A longitudinal analysis of self-efficacy and its sources
2021
The beliefs children hold about their capabilities as readers are known to influence their reading achievement. The aim of this study was to extend previous work by examining trajectories of change in reading self-efficacy among primary school students (N = 1327) and the relations between the trajectories of self-efficacy and their hypothesized sources over 11 months. Using growth mixture modeling, we identified four trajectories of change in reading self-efficacy, involving increasing, stable, and declining trends. These trajectories of change in reading self-efficacy were associated with students’ varying experiences with the four sources of self-efficacy over time. Higher levels of maste…
SDSS DR7 superclusters. Morphology
2011
We study the morphology of a set of superclusters drawn from the SDSS DR7. We calculate the luminosity density field to determine superclusters from a flux- limited sample of galaxies from SDSS DR7, and select superclusters with 300 and more galaxies for our study. The morphology of superclusters is described with the fourth Minkowski functional V3, the morphological signature (the curve in the shapefinder's K1-K2 plane) and the shape parameter (the ratio of the shapefinders K1/K2). We investigate the supercluster sample using multidimensional normal mixture modelling, and use Abell clusters to identify our superclusters with known superclusters and to study the large-scale distribution of …
Modelling of Magnetic Resonance Spectra Using Mixtures for Binned and Truncated Data
2007
Magnetic Resonance Spectroscopy (MRS) provides the biochemical composition of a tissue under study. This information is useful for the in-vivo diagnosis of brain tumours. Prior knowledge of the relative position of the organic compound contributions in the MRS suggests the development of a probabilistic mixture model and its EM-based Maximum Likelihood Estimation for binned and truncated data. Experiments for characterizing and classifying Short Time Echo (STE) spectra from brain tumours are reported.
Multimodality of rich clusters from the SDSS DR8 within the supercluster-void network
2012
We study the relations between the multimodality of galaxy clusters drawn from the SDSS DR8 and the environment where they reside. As cluster environment we consider the global luminosity density field, supercluster membership, and supercluster morphology. We use 3D normal mixture modelling, the Dressler-Shectman test, and the peculiar velocity of cluster main galaxies as signatures of multimodality of clusters. We calculate the luminosity density field to study the environmental densities around clusters, and to find superclusters where clusters reside. We determine the morphology of superclusters with the Minkowski functionals and compare the properties of clusters in superclusters of dif…
Risk Preference Heterogeneity and Multiple Demand for Insurance
2010
We examined the relationship between unobserved risk preferences and four insurance purchase decisions: health Medigap insurance, long-term insurance, life insurance and annuity. Standard economic theory assumes that individuals take decision over a set of risky domains according to their own risk preferences which are stable across decision contexts. This assumption of context-invariant risk preference has caused debate in the literature concerning its validity. Using data from the Health and Retirement Study, we exploit latent class analysis to identify conditional on predicted and realized risk how heterogeneity in risk preferences affects multiple insurance demand. Our results provide e…
Classification of SD-OCT Volumes for DME Detection: An Anomaly Detection Approach
2016
International audience; Diabetic Macular Edema (DME) is the leading cause of blindness amongst diabetic patients worldwide. It is characterized by accumulation of water molecules in the macula leading to swelling. Early detection of the disease helps prevent further loss of vision. Naturally, automated detection of DME from Optical Coherence Tomography (OCT) volumes plays a key role. To this end, a pipeline for detecting DME diseases in OCT volumes is proposed in this paper. The method is based on anomaly detection using Gaussian Mixture Model (GMM). It starts with pre-processing the B-scans by resizing, flattening, filtering and extracting features from them. Both intensity and Local Binar…
Developmental trajectories of school burnout: Evidence from two longitudinal studies
2014
Abstract To examine school burnout trajectories, in Study 1, 15-year-old adolescents ( N = 614) completed the School Burnout Inventory twice during their final term of comprehensive school and twice after the transition to upper secondary high school or vocational school. In Study 2, school burnout in 17-year-old adolescents was measured twice annually ( N = 575) during their upper secondary education. In Study 1, growth mixture modeling for school burnout yielded a four-latent-group solution: 60% of the adolescents showed a low and stable level of school burnout, 29% increasing burnout, 3% strongly increasing burnout and 8% high-decreasing school burnout. In Study 2, we identified two la…
Career goal-related success expectations across two educational transitions: A seven-year longitudinal study
2013
The purpose of this seven-year longitudinal study was to examine the trajectories of adolescents' career goal-related success expectations during two educational transitions. Altogether 850 (48% female, M Age = 16) participants reported their success expectations for their career-related goals, first in the last year of comprehensive school and four times during the following seven years. Overall, the success expectations showed a significant increase. However, there was considerable heterogeneity in the development of these expectations. Growth Mixture Modeling showed that four trajectories fitted the data best: high-increasing (78%), low-increasing (9%), decreasing (6%) and U-shaped (7%).…