Colligation and Cross Moment-Based Approaches for Independent Component Analysis

Diplomityössä on käsitelty uudenlaisia menetelmiä riippumattomien komponenttien analyysiin(ICA): Menetelmät perustuvat colligaatioon ja cross-momenttiin. Colligaatio menetelmä perustuu painojen colligaatioon. Menetelmässä on käytetty kahden tyyppisiä todennäköisyysjakaumia yhden sijasta joka perustuu yleiseen itsenäisyyden kriteeriin. Työssä on käytetty colligaatio lähestymistapaa kahdella asymptoottisella esityksellä. Gram-Charlie ja Edgeworth laajennuksia käytetty arvioimaan todennäköisyyksiä näissä menetelmissä. Työssä on myös käytetty cross-momentti menetelmää joka perustuu neljännen asteen cross-momenttiin. Menetelmä on hyvin samankaltainen FastICA algoritmin kanssa. Molempia menetelmiä on tarkasteltu lineaarisella kahden itsenäisen muuttajan sekoituksella. Lähtö signaalit ja sekoitetut matriisit ovattuntemattomia signaali lähteiden määrää lukuunottamatta. Työssä on vertailtu colligaatio menetelmään ja sen modifikaatioita FastICA:an ja JADE:en. Työssä on myös tehty vertailu analyysi suorituskyvyn ja keskusprosessori ajan suhteen cross-momenttiin perustuvien menetelmien, FastICA:n ja JADE:n useiden sekoitettujen parien kanssa.

Thyroid function in the elderly and sex hormones in elderly men: reference intervals and associations with health

Aims: The aims were to create clinically feasible reference intervals for thyroidstimulating hormone (TSH) and free thyroxine (FT4) and to analyze associations between thyroid function and self-rated health, neuropsychiatric symptoms, depression and dementia in the elderly. The second aim was also to establish reference intervals for sex hormones and to analyze associations between sex hormone levels and self-rated health, symptoms, depression and dementia in elderly men. Subjects and methods: The study population comprised 1252 subjects aged 65 years or over, living in the municipality of Lieto, south-western Finland. Self-rated health, life satisfaction, symptoms, depression, and dementia were assessed with specific questions, clinical examination and tools such as the Zung Self-report Depression Scale and the Mini-Mental State Examination. Independent variables were dichotomized, and associations of these variables with TSH, FT4 or sex hormone levels were assessed. Levels of TSH and FT4 in thyroid disease–free women and women treated with thyroxine were also compared. Results: Elevated concentrations of thyroid peroxidase antibodies (TPOAb) or thyroglobulin antibodies (TgAb) were found to have a marked effect on the upper reference limit for TSH among women, who were thyroid antibody positive more higher than suggested in several recent guidelines. After age adjustment, there were no associations between TSH levels and self-rated health, life satisfaction, or most neuropsychiatric symptoms in the thyroid disease-free population. Although women with thyroxine treatment for primary hypothyroidism had far higher TSH levels than thyroid disease-free women, there were no differences between thyroid-disease free women and women with stable thyroxine treatment regarding self-rated health, life satisfaction or symptoms. Age had a significant positive association with luteinizing hormone (LH), follicle 2 practice, one range in men aged 65 years or over can be used for T, E2 and FSH measured with the AutoDelfia method, but two separate reference intervals should be used for fT, LH and SHBG. After adjustment for age, higher levels of T and fT were associated with better self-rated health (SRH) in the reference population. After adjustment for age and body mass index (BMI), there were no associations between sex hormone concentrations and self-rated health, life satisfaction or most symptoms in concentration. Conclusion: Age-specific reference intervals were derived for thyroid function and sex hormones based on comprehensive data from a community-dwelling population with a high participation rate. The results do not support the need to decrease the upper reference limit for TSH or to lower the optimal TSH target in levothyroxine treatment in older adults, as recommended in recent guidelines. Older age or being overweight symptoms among elderly men. The associations of single symptoms with T levels were inconsistent among elderly men, although the association of low T level with diagnosed depression might be clinically significant.

Evaluation of Teacher Education Programs by Students and Graduates

The purpose of this research was to do a repeated cross-sectional research on class teachers who study in the 4th year and also graduated at the Faculty of Education, University of Turku between the years of 2000 through 2004. Specifically, seven research questions were addressed to target the main purpose of the study: How do class teacher education masters’ degree senior students and graduates rate “importance; effectiveness; and quality” of training they have received at the Faculty of Education? Are there significant differences between overall ratings of importance; effectiveness and quality of training by year of graduation, sex, and age (for graduates) and sex and age (for senior students)? Is there significant relationship between respondents’ overall ratings of importance; effectiveness and their overall ratings of the quality of training and preparation they have received? Are there significant differences between graduates and senior students about importance, effectiveness, and quality of teacher education programs? And what do teachers’ [Graduates] believe about how increasing work experience has changed their opinions of their preservice training? Moreover the following concepts related to the instructional activities were studied: critical thinking skills, communication skills, attention to ethics, curriculum and instruction (planning), role of teacher and teaching knowledge, assessment skills, attention to continuous professional development, subject matters knowledge, knowledge of learning environment, and using educational technology. Researcher also tried to find influence of some moderator variables e.g. year of graduation, sex, and age on the dependent and independent variables. This study consisted of two questionnaires (a structured likert-scale and an open ended questionnaire). The population in study 1 was all senior students and 2000-2004 class teacher education masters’ degree from the departments of Teacher Education Faculty of Education at University of Turku. Of the 1020 students and graduates the researcher was able to find current addresses of 675 of the subjects and of the 675 graduates contacted, 439 or 66.2 percent responded to the survey. The population in study 2 was all class teachers who graduated from Turku University and now work in the few basic schools (59 Schools) in South- West Finland. 257 teachers answered to the open ended web-based questions. SPSS was used to produce standard deviations; Analysis of Variance; Pearson Product Moment Correlation (r); T-test; ANOVA, Bonferroni post-hoc test; and Polynomial Contrast tests meant to analyze linear trend. An alpha level of .05 was used to determine statistical significance. The results of the study showed that: A majority of the respondents (graduates and students) rated the overall importance, effectiveness and quality of the teacher education programs as important, effective and good. Generally speaking there were only a few significant differences between the cohorts and groups related to the background variables (gender, age). The different cohorts were rating the quality of the programs very similarly but some differences between the cohorts were found in the importance and effectiveness ratings. Graduates of 2001 and 2002 rated the importance of the program significantly higher than 2000 graduates. The effectiveness of the programs was rated significantly higher by 2001 and 2003 graduates than other groups. In spite of these individual differences between cohorts there were no linear trends among the year cohorts in any measure. In respondents’ ratings of the effectiveness of teacher education programs there was significant difference between males and females; females rated it higher than males. There were no significant differences between males’ and females’ ratings of the importance and quality of programs. In the ratings there was only one difference between age groups. Older graduates (35 years or older) rated the importance of the teacher training significantly higher that 25-35 years old graduates. In graduates’ ratings there were positive but relatively low correlations between all variables related to importance, effectiveness and quality of Teacher Education Programs. Generally speaking students’ ratings about importance, effectiveness and quality of teacher education program were very positive. There was only one significant difference related to the background variables. Females rated higher the effectiveness of the program. The comparison of students’ and graduates’ perception about importance, effectiveness, and quality of teacher education programs showed that there were no significant differences between graduates and students in the overall ratings. However there were differences in some individual variables. Students rated higher in importance of “Continuous Professional Development”, effectiveness of “Critical Thinking Skills” and “Using Educational Technology” and quality of “Advice received from the advisor”. Graduates rated higher in importance of “Knowledge of Learning Environment” and effectiveness of “Continuous Professional Development”. According to the qualitative data of study 2 some graduates expressed that their perceptions have not changed about the importance, effectiveness, and quality of training that they received during their study time. They pointed out that teacher education programs have provided them the basic theoretical/formal knowledge and some training of practical routines. However, a majority of the teachers seems to have somewhat critical opinions about the teacher education. These teachers were not satisfied with teacher education programs because they argued that the programs failed to meet their practical demands in different everyday situations of the classroom e.g. in coping with students’ learning difficulties, multiprofessional communication with parents and other professional groups (psychologists and social workers), and classroom management problems. Participants also emphasized more practice oriented knowledge of subject matter, evaluation methods and teachers’ rights and responsibilities. Therefore, they (54.1% of participants) suggested that teacher education departments should provide more practice-based courses and programs as well as closer collaboration between regular schools and teacher education departments in order to fill gap between theory and practice.

Taloushallinnon ulkoistaminen: pienten osakeyhtiöiden näkemyksiä ulkoistetun taloushallinnon palveluntarjonnasta

Tämän tutkimuksen aiheena on pienten yhtiöiden taloushallinto: miten taloushallinnon tuottamaa tietoa hyödynnetään yrityksissä, kuinka tyytyväisiä taloushallinnon tuottamaan tietoon ollaan ja minkälainen on yrityksen ja tilitoimiston välinen suhde. Myös johdon laskentatoimi on yksi tarkastelun osa-alue. Pääpaino tutkimuksessa on tilastollisella analyysilla, jossa selvitetään pääasiassa Oneway anova- ja T- testein onko ulkoistamisen tasolla, tilintarkastajasuhteella, perheyrittäjyydellä ja käytetyn tilitoimiston koolla merkitystä tyytyväisyyteen yrityksen taloushallintoa ja tilitoimistosuhdetta kohtaan. Tutkimuksen tuloksena löytyi joitakin eroja. Eniten seuratuiksi taloushallinnon muodoiksi nousivat kassavirran ja kannattavuuden seuranta ja johdon laskentatoimen raportit eri muodoissaan. Tilitoimiston ja yrityksen suhde nähdään usein pohjautuvan pääasiassa lakisääteisten vaatimusten täyttämiseen ja kustannussäästöjen hakuun, mutta selkeää potentiaalia tilitoimiston perinteisen roolin laajentamiseen on olemassa.

Determinants of credit risk in secured loans – Evidence from the auto loan industry

The purpose of this study is to examine attributes which have explanation power to the probability of default or serious overdue in secured auto loans. Another goal is to find out differences between defaulted loans and loans which have had payment difficulties but survived without defaulting. 19 independent variables used in this study reflect information available at the time of credit decision. These variables were tested with logistic regression and backward elimination procedure. The data includes 8931 auto loans from a Finnish finance company. 1118 of the contracts were taken by company customers and 7813 by private customers. 130 of the loans defaulted and 584 had serious payment problems but did not default. The maturities of those loans were from one month to 60 months and they have ended during year 2011. The LTV (loan-to-value) variable was ranked as the most significant explainer because of its strong positive relationship with probability of payment difficulties. Another important explainer in this study was the credit rating variable which got a negative relationship with payment problems. Also maturity and car age performed well having both a positive relationship with the probability of payment problems. When compared default and serious overdue situations, the most significant differences were found in the roles of LTV, Maturity and Gender variables.