Reliabilität - die Genauigkeit einer Messung (Version 1.1)

Die Reliabilität beschreibt die Genauigkeit einer Messung. In diesem Beitrag wird das Konzept Reliabilität definiert und es wird erläutert, warum die Reliabilität einer Messung relevant ist. Danach wird diskutiert, welche Modellannahmen getroffen werden müssen, um die Reliabilität einer Messung zu schätzen und es werden fünf Methoden zum Schätzen der Reliabilität vorgestellt: die Re-Test Korrelation, die Parallel-Test Korrelation, die Split-Half Korrelation, die interne Konsistenz und das Schätzen der Reliabilität mit Strukturgleichungsmodellen. Abschließend wird in knapper Form auf Gemeinsamkeiten und Unterschiede der klassischen Testtheorie und der Item-Response Theorie und deren Bedeutung für die Schätzung der Reliabilität eingegangen

Evaluation of fluoride release from experimental TiF4 and NaF varnishes in vitro

Fluoride varnishes play an important role in the prevention of dental caries, promoting the inhibition of demineralization and the increase of remineralization. OBJECTIVE: This study aimed to analyze the amount of fluoride released into water and artificial saliva from experimental TiF(4 )and NaF varnishes, with different concentrations, for 12 h. MATERIAL AND METHODS: Fluoride varnishes were applied on acrylic blocks and then immersed in 10 ml of deionized water and artificial saliva in polystyrene bottles. The acrylic blocks were divided in seven groups (n=10): 1.55% TiF(4 )varnish (0.95% F, pH 1.0); 3.10% TiF(4 )varnish (1.90% F, pH 1.0); 3.10% and 4% TiF(4 )varnish (2.45% F, pH 1.0); 2.10% NaF varnish (0.95% F, pH 5.0); 4.20% NaF varnish (1.90% F, pH 5.0); 5.42% NaF varnish (2.45% F, pH 5.0) and control (no treatment, n=5). The fluoride release was analyzed after 1/2, 1, 3, 6, 9 and 12 h of exposure. The analysis was performed using an ion-specific electrode coupled to a potentiometer. Two-way ANOVA and Bonferroni's test were applied for the statistical analysis (p<0.05). RESULTS: TiF(4 )varnishes released larger amounts of fluoride than NaF varnishes during the first 1/2 h, regardless of their concentration; 4% TiF(4) varnish released more fluoride than NaF varnishes for the first 6 h. The peak of fluoride release occurred at 3 h. There was a better dose-response relationship among the varnishes exposed to water than to artificial saliva. CONCLUSIONS: The 3.10% and 4% TiF(4 )-based varnishes have greater ability to release fluoride into water and artificial saliva compared to NaF varnish; however, more studies must be conducted to elucidate the mechanism of action of TiF(4 )varnish on tooth surface

Social Media, Gender and the Mediatisation of War: Exploring the German Armed Forces’ Visual Representation of the Afghanistan Operation on Facebook

Studies on the mediatisation of war point to attempts of governments to regulate the visual perspective of their involvements in armed conflict – the most notable example being the practice of ‘embedded reporting’ in Iraq and Afghanistan. This paper focuses on a different strategy of visual meaning-making, namely, the publication of images on social media by armed forces themselves. Specifically, we argue that the mediatisation of war literature could profit from an increased engagement with feminist research, both within Critical Security/Critical Military Studies and within Science and Technology Studies that highlight the close connection between masculinity, technology and control. The article examines the German military mission in Afghanistan as represented on the German armed forces’ official Facebook page. Germany constitutes an interesting, and largely neglected, case for the growing literature on the mediatisation of war: its strong antimilitarist political culture makes the representation of war particularly delicate. The paper examines specific representational patterns of Germany’s involvement in Afghanistan and discusses the implications which arise from what is placed inside the frame of visibility and what remains out of its view