If the ratio m/p tends to zero, where m is the number of factors m and p the number of observable variables, then the inverse diagonal element of the inverted observable covariance matrix (σ pjj) -1 tends to the corresponding unique variance ψ jj for almost all of these (Guttman, 1956). If the smallest singular value of the loadings matrix from Common Factor Analysis tends to infinity as p increases, then m/p tends to zero. The same condition is necessary and sufficient for (σ pjj) -1 to tend to ψ jj for all of these. Several related conditions are discussed. © 2006 The Psychometric Society.
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The assumptions of the model for factor analysis do not exclude a class of indeterminate covariances between factors and error variables (Grayson, 2003). The construction of all factors of the model for factor analysis is generalized to incorporate indeterminate factor-error covariances. A necessary and sufficient condition is given for indeterminate factor-error covariances to be arbitrarily small, for mean square convergence of the regression predictor of factor scores, and for the existence of a unique determinate factor and error variable. The determinate factor and error variable are uncorrelated and satisfy the defining assumptions of factor analysis. Several examples are given to illustrate the results.
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A previous study found a variety of unusual sexual interests to cluster in a five-factor structure, namely submission/masochism, forbidden sexual activities, dominance / sadism, mysophilia, and fetishism (Schippers et al., 2021). The current study was an empirical replication to examine whether these findings generalized to a representative population sample. An online, anonymous sample (N = 256) representative of the Dutch adult male population rated 32 unusual sexual interests on a scale from 1 (very unappealing) to 7 (very appealing). An exploratory factor analysis assessed whether similar factors would emerge as in the original study. A subsequent confirmatory factor analysis served to confirm the factor structure. Four slightly different factors of sexual interest were found: extreme, illegal and mysophilic sexual activities; light BDSM without real pain or suffering; heavy BDSM that may include pain or suffering; and illegal but lower-sentenced and fetishistic sexual activities. The model fit was acceptable. The representative replication sample was more sexually conservative and showed less sexual engagement than the original convenience sample. On a fundamental level, sexual interest in light BDSM activities and extreme, forbidden, and mysophilic activities seem to be relatively separate constructs.
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Abstract: Background: Chronic obstructive pulmonary disease (COPD) and asthma have a high prevalence and disease burden. Blended self-management interventions, which combine eHealth with face-to-face interventions, can help reduce the disease burden. Objective: This systematic review and meta-analysis aims to examine the effectiveness of blended self-management interventions on health-related effectiveness and process outcomes for people with COPD or asthma. Methods: PubMed, Web of Science, COCHRANE Library, Emcare, and Embase were searched in December 2018 and updated in November 2020. Study quality was assessed using the Cochrane risk of bias (ROB) 2 tool and the Grading of Recommendations, Assessment, Development, and Evaluation. Results: A total of 15 COPD and 7 asthma randomized controlled trials were included in this study. The meta-analysis of COPD studies found that the blended intervention showed a small improvement in exercise capacity (standardized mean difference [SMD] 0.48; 95% CI 0.10-0.85) and a significant improvement in the quality of life (QoL; SMD 0.81; 95% CI 0.11-1.51). Blended intervention also reduced the admission rate (relative ratio [RR] 0.61; 95% CI 0.38-0.97). In the COPD systematic review, regarding the exacerbation frequency, both studies found that the intervention reduced exacerbation frequency (RR 0.38; 95% CI 0.26-0.56). A large effect was found on BMI (d=0.81; 95% CI 0.25-1.34); however, the effect was inconclusive because only 1 study was included. Regarding medication adherence, 2 of 3 studies found a moderate effect (d=0.73; 95% CI 0.50-0.96), and 1 study reported a mixed effect. Regarding self-management ability, 1 study reported a large effect (d=1.15; 95% CI 0.66-1.62), and no effect was reported in that study. No effect was found on other process outcomes. The meta-analysis of asthma studies found that blended intervention had a small improvement in lung function (SMD 0.40; 95% CI 0.18-0.62) and QoL (SMD 0.36; 95% CI 0.21-0.50) and a moderate improvement in asthma control (SMD 0.67; 95% CI 0.40-0.93). A large effect was found on BMI (d=1.42; 95% CI 0.28-2.42) and exercise capacity (d=1.50; 95% CI 0.35-2.50); however, 1 study was included per outcome. There was no effect on other outcomes. Furthermore, the majority of the 22 studies showed some concerns about the ROB, and the quality of evidence varied. Conclusions: In patients with COPD, the blended self-management interventions had mixed effects on health-related outcomes, with the strongest evidence found for exercise capacity, QoL, and admission rate. Furthermore, the review suggested that the interventions resulted in small effects on lung function and QoL and a moderate effect on asthma control in patients with asthma. There is some evidence for the effectiveness of blended self-management interventions for patients with COPD and asthma; however, more research is needed. Trial Registration: PROSPERO International Prospective Register of Systematic Reviews CRD42019119894; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=119894
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Sufficient conditions for mean square convergence of factor predictors in common factor analysis are given by Guttman, by Williams, and by Schneeweiss and Mathes. These conditions do not hold for confirmatory factor analysis or when an error variance equals zero (Heywood cases). Two sufficient conditions are given for the three basic factor predictors and a predictor from rotated principal components analysis to converge to the factors of the model for confirmatory factor analysis, including Heywood cases. For certain model specifications the conditions are necessary. The conditions are sufficient for the existence of a unique true factor. A geometric interpretation is given for factor indeterminacy and mean square convergence of best linear factor prediction.
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Cybercrime – en daarmee cybersecurity – is een groot maatschappelijk probleem. De criminologische bestudering van cybercrime staat nog in de kinderschoenen. Het is echter niet alleen noodzakelijk om fundamenteel wetenschappelijk onderzoek uit te voeren (‘de lange termijn’), maar ook om met de praktijk de acute problemen en uitdagingen van vandaag en morgen te onderzoeken. Het merendeel van het onderzoek op dit gebied – en dan heb ik het over zowel fundamenteel wetenschappelijk als praktijkgericht onderzoek – komt tot nu toe uit de hoek van de technische wetenschappen. Technologie speelt natuurlijk ook een belangrijke rol bij cyberincidenten, maar we hebben het over mensen die cyberaanvallen uitvoeren, mensen die – wetend of onwetend – meewerken aan die aanvallen, mensen die slachtoffer worden en mensen die zich bezighouden met het tegenhouden van cyberaanvallen. Empirisch onderzoek naar de menselijke factor bij cybercrime en cybersecurity is schaars. De onder mijn redactie recent uitgebrachte onderzoeksagenda ‘The human factor in cybercrime en cybersecurity’ maakt dit helder.1 In die onderzoeksagenda zijn tientallen onderwerpen geïdentificeerd waar de komende jaren onderzoek naar moet worden gedaan omdat basale kennis ontbreekt. Tegelijkertijd zit het werkveld te springen om bruikbare kennis over manieren om zich te beschermen tegen cyberaanvallen. Dat laatste is iets wat we zeker gemerkt hebben het afgelopen jaar. Al voor de officiële start van het lectoraat Cybersecurity in het midden- en kleinbedrijf (mkb) stroomden de verzoeken binnen van gemeenten, brancheorganisaties en bedrijven om gezamenlijk onderzoek te doen. Dit is dan ook de reden dat we, ondanks dat het lectoraat nog geen jaar geleden is ingesteld, al flink wat onderzoeken voor en met de praktijk uitvoeren. De constatering dat onderzoek naar de menselijke factor binnen cybercrime en cybersecurity nog in de kinderschoenen staat terwijl er een grote vraag is naar evidence-based praktisch toepasbare kennis, is de reden dat De Haagse Hogeschool (HHs) en het Nederlands Studiecentrum Criminaliteit en Rechtshandhaving (NSCR) de handen ineengeslagen hebben voor de totstandkoming van dit lectoraat. Zowel De HHs als het NSCR hebben cybersecurity en cybercrime al enkele jaren geleden als prioriteit benoemd en hebben elk afzonderlijk onderzoeksprogramma’s op dit gebied. Voor De HHs geldt dat onderzoeken toepassingsgericht moeten zijn en dat de nieuwste onderzoeksmethoden en -technieken moeten worden toegepast om hoogwaardige producten op te leveren. Voor het NSCR geldt dat onderzoeken ook fundamentele kennis moeten opleveren. Het is echter steeds duidelijker dat bij onderzoek naar cybercrime en cybersecurity het beste van beide werelden nodig is. Het lectoraat heeft dan ook de nadrukkelijke opdracht deze twee onderzoeksprogramma’s te verbinden. Ik zal in deze inleiding een beknopte schets geven van de onderzoeksprogramma’s van deze organisaties en van de toekomstige onderzoeken binnen het lectoraat. LinkedIn: https://www.linkedin.com/in/rutgerleukfeldt/
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The aim of this study was to understand the motives for using the Internet, and its associations with users' attitudes, social values, and relational involvement. Also, this study attempted to crossculturally compare the difference in the pattern of motives and the associations among three countries ' the US, the Netherlands, and S. Korea. The design of methods was based on examination and revision of uses and gratification approach toward Internet users. Findings from factor analysis revealed that information seeking and Self-Improvement were the dominant and common reasons for using the Internet across three countries. The differences in the composition of motives in each country were also reported. Strong correlations across countries were found between all the motives and satisfaction of the Internet. Expectation and positive evaluation of the Internet were also important attitudes associated with Internet use motives. Postmaterialist value showed strong association with motives of information seeking and Self-Improvement. Community involvement was significantly associated with Internet use motives in Korean users.
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Objective: To examine the underlying factor structure and psychometric properties of the Assessment of Self-management in Anxiety and Depression (ASAD) questionnaire, which was specifically designed for patients with (chronic) anxiety and depressive disorders. Moreover, this study assesses whether the number of items in the ASAD can be reduced without significantly reducing its precision. Methods: The ASAD questionnaire was completed by 171 participants across two samples: one sample comprised patients with residual anxiety or depressive symptoms, while the other consisted of patients who have been formally diagnosed with a chronic anxiety or depressive disorder. All participants had previously undergone treatment. Both exploratory (EFA) and confirmatory factor analyses (CFA) were conducted. Internal consistency and test–retest reliability were also assessed. Results: Both EFA and CFA indicated three solid factors: Seeking support, Daily life strategies and Taking ownership [Comparative Fit Index = 0.80, Tucker Lewis Index = 0.78, Root Mean Square Error of Approximation = 0.09 (CI 0.08–1.00), Standardized Root Mean Square Residual = 0.09 ($2 = 439.35, df = 168)]. The ASAD was thus reduced from 45 items to 21 items, which resulted in the ASAD-Short Form (SF). All sub-scales had a high level of internal consistency (> a = 0.75) and test–retest reliability (ICC > 0.75). Discussion: The first statistical evaluation of the ASAD indicated a high level of internal consistency and test–retest reliability, and identified three distinctive factors. This could aid patients and professionals’ assessment of types of self-management used by the patient. Given that this study indicated that the 21-item ASAD-SF is appropriate, this version should be further explored and validated among a sample of patients with (chronic or partially remitted) anxiety and depressive disorders. Alongside this, to increase generalizability, more studies are required to examine the English version of the ASAD within other settings and countries.
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Introduction: In the Netherlands, Diagnostic Reference Levels (DRLs) have not been based on a national survey as proposed by ICRP. Instead, local exposure data, expert judgment and the international scientific literature were used as sources. This study investigated whether the current DRLs are reasonable for Dutch radiological practice. Methods: A national project was set up, in which radiography students carried out dose measurements in hospitals supervised by medical physicists. The project ran from 2014 to 2017 and dose values were analysed for a trend over time. In the absence of such a trend, the joint yearly data sets were considered a single data set and were analysed together. In this way the national project mimicked a national survey. Results: For six out of eleven radiological procedures enough data was collected for further analysis. In the first step of the analysis no trend was found over time for any of these procedures. In the second step the joint analysis lead to suggestions for five new DRL values that are far below the current ones. The new DRLs are based on the 75 percentile values of the distributions of all dose data per procedure. Conclusion: The results show that the current DRLs are too high for five of the six procedures that have been analysed. For the other five procedures more data needs to be collected. Moreover, the mean weights of the patients are higher than expected. This introduces bias when these are not recorded and the mean weight is assumed to be 77 kg. Implications for practice: The current checking of doses for compliance with the DRLs needs to be changed. Both the procedure (regarding weights) and the values of the DRLs should be updated.
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We show how to estimate a Cronbach's alpha reliability coefficient in Stata after running a principal component or factor analysis. Alpha evaluates to what extent items measure the same underlying content when the items are combined into a scale or used for latent variable. Stata allows for testing the reliability coefficient (alpha) of a scale only when all items receive homogenous weights. We present a user-written program that computes reliability coefficients when implementation of principal component or factor analysis shows heterogeneous item loadings. We use data on management practices from Bloom and Van Reenen (2010) to explain how to implement and interpret the adjusted internal consistency measure using afa.
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