Search results for "ta112"
showing 10 items of 69 documents
Adjusting for selective non-participation with re-contact data in the FINRISK 2012 survey
2018
Aims: A common objective of epidemiological surveys is to provide population-level estimates of health indicators. Survey results tend to be biased under selective non-participation. One approach to bias reduction is to collect information about non-participants by contacting them again and asking them to fill in a questionnaire. This information is called re-contact data, and it allows to adjust the estimates for non-participation. Methods: We analyse data from the FINRISK 2012 survey, where re-contact data were collected. We assume that the respondents of the re-contact survey are similar to the remaining non-participants with respect to the health given their available background informa…
Comprehensive geriatric assessment decreases prevalence of orthostatic hypotension in older persons
2013
Background: Orthostatic hypotension (OH) is associated with significant morbidity and mortality among older people. We have studied whether its prevalence can be reduced by a Comprehensive Geriatric Assessment (CGA). Study design and setting: 1000 randomly-selected persons aged ≥75 years were divided into intervention ( n = 500) and control groups ( n = 500). We focused on those subjects in whom an orthostatic blood pressure test had been performed at least once during the study period (2004–2007) ( n = 365 and 332 for intervention and control groups, respectively). A CGA, including evaluation of the adequacy of the medication, was performed annually in the intervention group but not in th…
The squared symmetric FastICA estimator
2017
In this paper we study the theoretical properties of the deflation-based FastICA method, the original symmetric FastICA method, and a modified symmetric FastICA method, here called the squared symmetric FastICA. This modification is obtained by replacing the absolute values in the FastICA objective function by their squares. In the deflation-based case this replacement has no effect on the estimate since the maximization problem stays the same. However, in the symmetric case we obtain a different estimate which has been mentioned in the literature, but its theoretical properties have not been studied at all. In the paper we review the classic deflation-based and symmetric FastICA approaches…
Deflation-Based FastICA With Adaptive Choices of Nonlinearities
2014
Deflation-based FastICA is a popular method for independent component analysis. In the standard deflation-base d approach the row vectors of the unmixing matrix are extracted one after another always using the same nonlinearities. In prac- tice the user has to choose the nonlinearities and the efficiency and robustness of the estimation procedure then strongly depends on this choice as well as on the order in which the components are extracted. In this paper we propose a novel adaptive two- stage deflation-based FastICA algorithm that (i) allows one to use different nonlinearities for different components and (ii) optimizes the order in which the components are extracted. Based on a consist…
Classification and retrieval on macroinvertebrate image databases
2011
Aquatic ecosystems are continuously threatened by a growing number of human induced changes. Macroinvertebrate biomonitoring is particularly efficient in pinpointing the cause-effect structure between slow and subtle changes and their detrimental consequences in aquatic ecosystems. The greatest obstacle to implementing efficient biomonitoring is currently the cost-intensive human expert taxonomic identification of samples. While there is evidence that automated recognition techniques can match human taxa identification accuracy at greatly reduced costs, so far the development of automated identification techniques for aquatic organisms has been minimal. In this paper, we focus on advancing …
A cautionary note on the finite sample behavior of maximal reliability.
2019
Several calls have been made for replacing coefficient α with more contemporary model-based reliability coefficients in psychological research. Under the assumption of unidimensional measurement scales and independent measurement errors, two leading alternatives are composite reliability and maximal reliability. Of these two, the maximal reliability statistic, or equivalently Hancock's H, has received a significant amount of attention in recent years. The difference between composite reliability and maximal reliability is that the former is a reliability index for a scale mean (or unweighted sum), whereas the latter estimates the reliability of a scale score where indicators are weighted di…
Factorial Validity and Reliability of the Curricular Goals in Physical Education Questionnaire
2015
This study aimed to examine the validity and reliability of an instrument designed to measure student perceptions of curricular goals in physical education, the Curricular Goals in Physical Education Questionnaire. Participants were 879 Finnish students from grades 7 to 9 (412 girls, 467 boys; mean age 13.81). An exploratory factor analysis was performed on Sample 1 (n = 287), revealing a four-factor solution and suggesting that factor structure be cross-validated with confirmatory factor analysis in Sample 2 (n = 592). Confirmatory factor analysis demonstrated an acceptable fit and supported the four-factor model. Tests for gender invariance supported configural, metric, and scalar invaria…
Religion, Religiosity, Sex, and Willingness to Express Political Opinions: A Spiral of Silence Analysis of the 2008 U.S. Presidential Election
2014
This study analyzes the extent to which an individual's sex, religion, and religiosity influence their willingness to voice an opinion about Barack Obama's ethnicity in the 2008 election. Results from 569 college students surveyed reveal sex to be a nonsignificant predictor, whereas religion and religiosity significantly influence willingness to voice an opinion about Obama's ethnicity. More religious individuals were more likely to voice an opinion about Obama's ethnicity as a voting issue in the campaign. There were significant differences among religious groups and their willingness to voice an opinion on this issue.
Selection bias was reduced by recontacting nonparticipants
2016
Objective One of the main goals of health examination surveys is to provide unbiased estimates of health indicators at the population level. We demonstrate how multiple imputation methods may help to reduce the selection bias if partial data on some nonparticipants are collected. Study Design and Setting In the FINRISK 2007 study, a population-based health study conducted in Finland, a random sample of 10,000 men and women aged 25–74 years were invited to participate. The study included a questionnaire data collection and a health examination. A total of 6,255 individuals participated in the study. Out of 3,745 nonparticipants, 473 returned a simplified questionnaire after a recontact. Both…
Correcting for non-ignorable missingness in smoking trends
2015
Data missing not at random (MNAR) is a major challenge in survey sampling. We propose an approach based on registry data to deal with non-ignorable missingness in health examination surveys. The approach relies on follow-up data available from administrative registers several years after the survey. For illustration we use data on smoking prevalence in Finnish National FINRISK study conducted in 1972-1997. The data consist of measured survey information including missingness indicators, register-based background information and register-based time-to-disease survival data. The parameters of missingness mechanism are estimable with these data although the original survey data are MNAR. The u…