80 s. : 14 tab.
- Keywords
- zdravotnictví, statistika, studie, příklady, sampling studies, health surveys, péče zdravotní - materiály WHO,
- Conspectus
- Veřejné zdraví a hygiena
- NML Fields
- sociální lékařství
- statistika, zdravotnická statistika
- veřejné zdravotnictví
- NML Publication type
- publikace WHO
xii, 239 s. : il., tab. ; 24 cm
- MeSH
- Statistics as Topic MeSH
- Public Health statistics & numerical data MeSH
- Investigative Techniques MeSH
- Research Design MeSH
- Sampling Studies MeSH
- Conspectus
- Veřejné zdraví a hygiena
- NML Fields
- veřejné zdravotnictví
- statistika, zdravotnická statistika
- veřejné zdravotnictví
- NML Publication type
- publikace WHO
This paper focuses on wrapper-based feature selection for a 1-nearest neighbor classifier. We consider in particular the case of a small sample size with a few hundred instances, which is common in biomedical applications. We propose a technique for calculating the complete bootstrap for a 1-nearest-neighbor classifier (i.e., averaging over all desired test/train partitions of the data). The complete bootstrap and the complete cross-validation error estimate with lower variance are applied as novel selection criteria and are compared with the standard bootstrap and cross-validation in combination with three optimization techniques - sequential forward selection (SFS), binary particle swarm optimization (BPSO) and simplified social impact theory based optimization (SSITO). The experimental comparison based on ten datasets draws the following conclusions: for all three search methods examined here, the complete criteria are a significantly better choice than standard 2-fold cross-validation, 10-fold cross-validation and bootstrap with 50 trials irrespective of the selected output number of iterations. All the complete criterion-based 1NN wrappers with SFS search performed better than the widely-used FILTER and SIMBA methods. We also demonstrate the benefits and properties of our approaches on an important and novel real-world application of automatic detection of the subthalamic nucleus.
- MeSH
- Models, Theoretical MeSH
- Sample Size * MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Validation Study MeSH
BACKGROUND: White matter abnormality has been recently proposed as a pathophysiological feature of schizophrenia (SZ). However, most of the data available has been gathered from chronic patients, and was therefore possibly confounded by factors such as duration of the disease, and treatment received. The extent and localization of these changes is also not clear. METHODS: We examined a population of early stage SZ patients using diffusion tensor imaging (DTI). 77 SZ patients and 60 healthy controls (HCs) were included in the analysis using Tract-Based Spatial Statistics (TBSS). We have also analyzed 250 randomly created subsets of the original cohort, to investigate the relation between the result of TBSS analysis, and the size of the sample studied. RESULTS: We have found a significant decrease in fractional anisotropy (FA) in the patient group. This change is present in most major white matter (WM) tracts including the corpus callosum, superior and inferior longitudinal fasciculi, inferior fronto-occipital fasciculus, and posterior thalamic radiation. Furthermore, we identified a clear trend towards an increase in the number and spatial extent of significant voxels reported, with an increasing number of subjects included in the analysis. CONCLUSION: Our study shows that FA is significantly decreased in patients at an early stage of schizophrenia, and that the extent of this finding is dependent on the size of studied sample; therefore underpowered studies might produce results with false spatial localization.
- MeSH
- Acute Disease MeSH
- Anisotropy MeSH
- White Matter pathology MeSH
- Diffusion Magnetic Resonance Imaging MeSH
- Adult MeSH
- Humans MeSH
- Brain pathology MeSH
- Prospective Studies MeSH
- Psychiatric Status Rating Scales MeSH
- Psychotic Disorders drug therapy pathology MeSH
- Schizophrenia drug therapy pathology MeSH
- Sample Size MeSH
- Diffusion Tensor Imaging MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Cílem práce bylo potvrdit nebo vyvrátit předpoklad, že konštitučné malá zadní jáma lehni je predispozicí pro vznik neurovaskulámího konfliktu. Za tímto účelem byly prověřovány indexy velikosti zadních jam U nemocných s prokázaným neurovaskulárním konfliktem a u nemocných náhodně vybraných ze standardní populace, kterou představují nemocní vyšetřovaní pro komoci mozkovou. V sérii 100 nemocných - 50 s neurovaskulárním konfliktem a 50 s komoci mozkovou - byla rozdílná velikost zadní jámy potvrzena.
Based on the hypothesis that a constitutionally small posterior fossa represents a predisposition for the development of neurovascular conflict, the aim of this article is either to confirm or to reject this hypothesis. To this end, indices of the size of the posterior fossa were studied, in patients with neurovascular conflict and, parallelly in patients randomly selected from the standard population. The latter group was represented by patients having suffered brain concussion. The investigation of a sample of 100 patients (50 with neurovascular conflict and 50 after brain concussion) showed a significantly different size of the posterior fossa in the group of patients with neurovascular conflict.
- MeSH
- Adult MeSH
- Research Support as Topic MeSH
- Hemifacial Spasm etiology MeSH
- Middle Aged MeSH
- Humans MeSH
- Trigeminal Neuralgia etiology MeSH
- Aged MeSH
- Congenital Abnormalities etiology MeSH
- Cranial Fossa, Posterior MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Aged MeSH
- Publication type
- Comparative Study MeSH
In this study we estimate sex and population affinity of Gravettian Predmostí (P) skulls using linear and geometric discriminant analysis (DA), and compare them with results of 2D geometric morphometrics (GM). We used the measurements of P3 and P9 males, P4 and P10 females, as originally estimated by Matiegka (1934), as well as two databases--the recent skull database of Howells and the fossil data of Henke. DA classifies the P skulls as robust and belonging to the "male" region, loosing the sensitivity of inter-population differences influenced by size factor. That is why this approach could not be applied. The geographic inter-population differences according to DA do not define P skull shapes as extreme. The influence of geographic variability could be stronger than the inter-sexual differences. Despite the chronological differences between databases and Gravettian skulls, these differences are a component of regional inter-population variability. According to our results, GM is more successful methodological approach than DA. Our previous sex estimation of P skulls with help of GM is completely in accordance with the classical morphoscopic estimation. However, an appropriate reference database is necessary in both the GM and DA approaches. For the sexing of skull with unknown population affinity, and with absence of appropriate reference database, we suggest to use the application of more subjective visual scoring methods.
- MeSH
- Databases, Factual MeSH
- Discriminant Analysis MeSH
- Adult MeSH
- Cephalometry methods MeSH
- Skull anatomy & histology MeSH
- Humans MeSH
- Sex Determination by Skeleton methods MeSH
- Organ Size MeSH
- Fossils * MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
