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71.
The authors provide a didactic treatment of nonlinear (categorical) principal components analysis (PCA). This method is the nonlinear equivalent of standard PCA and reduces the observed variables to a number of uncorrelated principal components. The most important advantages of nonlinear over linear PCA are that it incorporates nominal and ordinal variables and that it can handle and discover nonlinear relationships between variables. Also, nonlinear PCA can deal with variables at their appropriate measurement level; for example, it can treat Likert-type scales ordinally instead of numerically. Every observed value of a variable can be referred to as a category. While performing PCA, nonlinear PCA converts every category to a numeric value, in accordance with the variable's analysis level, using optimal quantification. The authors discuss how optimal quantification is carried out, what analysis levels are, which decisions have to be made when applying nonlinear PCA, and how the results can be interpreted. The strengths and limitations of the method are discussed. An example applying nonlinear PCA to empirical data using the program CATPCA (J. J. Meulman, W. J. Heiser, & SPSS, 2004) is provided. 相似文献
72.
Bakken IJ Wenzel HG Götestam KG Johansson A Oren A 《Scandinavian journal of psychology》2009,50(2):121-127
Most Norwegians are Internet users. We conducted a stratified probability sample study (Norway, 2007, age-group 16–74 years, N = 3,399, response rate 35.3%, 87.1% Internet users) to assess the prevalence of Internet addiction and at-risk Internet use by the Young Diagnostic Questionnaire (YDQ). The prevalence of Internet addiction (YDQ score 5–8) was 1.0% and an additional 5.2% were at-risk Internet users (YDQ score 3–4). Internet addiction and at-risk Internet use was strongly dependent on gender and age with highest prevalences among young males (16–29 years 4.1% and 19.0%, 30–39 years 3.3% and 10.7%). Logistic regression showed that male gender, young age, university level education, and an unsatisfactory financial situation were factors positively associated with "problematic Internet use" (at-risk and addicted use combined). Time spent on the Internet and prevalence of self-reported sleeping disorders, depression, and other psychological impairments increased linearly with YDQ score. Problematic Internet use clearly affects the lives of many people. 相似文献
73.
The aim of the present study was to investigate the relationship between resting heart rate variability (HRV) and cognitive functions during threat of shock. A Continuous Performance Task and a Working Memory Task were used to measure cognitive functions. Sixty-five male participants from the Royal Norwegian Navy participated. HRV was measured during baseline, test conditions and recovery. Participants were randomly assigned into non-threat and threat groups. Based on the median split of the high frequency (HF) spectral power, groups were divided into two additional groups. Overall, the high HRV participants showed superior performance on cognitive tasks independent of non-threat or threat conditions. During threat condition the low HRV group showed improved performance. Thus, individuals with high HRV were more stress tolerant and resilient in the face of environmental changes. The results from the study might have implications with regard to performance in operational settings, but also for other fields of psychological research such as individual differences, anxiety and coping. 相似文献
74.
Jeremy Davey James Freeman Anita Lavelle 《Transportation Research Part F: Traffic Psychology and Behaviour》2009,12(4):311-316
Police services in a number of Australian states and overseas jurisdictions have begun to implement or consider random road-side drug testing of drivers. This paper outlines research conducted to provide an estimate of the extent of drug driving in a sample of Queensland drivers in regional, rural and metropolitan areas. Oral fluid samples were collected from 2657 Queensland motorists and screened for illicit substances including cannabis (delta 9 tetrahydrocannibinol [THC]), amphetamines, ecstasy, and cocaine. Overall, 3.8% of the sample (n = 101) screened positive for at least one illicit substance, although multiple drugs were identified in a sample of 23 respondents. The most common drugs detected in oral fluid were ecstasy (n = 53), and cannabis (n = 46) followed by amphetamines (n = 23). A key finding was that cannabis was confirmed as the most common self-reported drug combined with driving and that individuals who tested positive to any drug through oral fluid analysis were also more likely to report the highest frequency of drug driving. Furthermore, a comparison between drug vs. drink driving detection rates for one region of the study, revealed a higher detection rate for drug driving (3.8%) vs. drink driving (0.8%). This research provides evidence that drug driving is relatively prevalent on Queensland roads, and may in fact be more common than drink driving. This paper will further outline the study findings’ and present possible directions for future drug driving research. 相似文献
75.
Objective Using the Internet can influence psychological well-being, for instance life satisfaction has been negatively related to
Internet uses. The first aim of this study was to compare the motives for Internet use and life satisfaction. The second aim
was to explore nation- and gender-based differences in Internet uses. Method The questionnaires related to Internet motives and life satisfaction, and were filled out by 300 medical students, including
150 Israeli students (75 females, 75 males) and 150 Hungarian students (75 females, 75 males). Results In the Israeli and Hungarian sample, the entertainment motive was rated the highest while the escape motive was rated the
lowest. There were significant differences between the Israeli male and female students in arousal and information-seeking,
while for the Hungarian male and female students there were significant differences for pass time. Life satisfaction was higher
in the Israeli sample. In both samples it was shown that the higher the life satisfaction was, the less likely the students
were to use the Internet for companionship purposes. Again in both samples, a higher life satisfaction predicted less frequent
use of the Internet for the social interaction motives. 相似文献
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Anita M. Superson 《The Journal of value inquiry》1996,30(1-2):213-227