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The overall aim of this thesis was to develop and validate a self-report instrument for perceived driver competence. The thesis includes six papers and a summary. All papers focus on perceived driver competence from a measurement perspective; that is, how to develop an instrument for perceived driver competence and how to use and interpret the scores from the instrument in a reliable and valid manner. Study I reviews how perceived driver competence has been measured in other studies and discusses these methods from a measurement perspective. Most studies have examined perceived driver competence by asking drivers to compare their own skill to that of the average driver. That method is problematic, since it is not possible to determine if drivers are overconfident or not, when empirical information of their own skills is missing. In order to examine if drivers overestimate their skills or not, perceived driver competence should be compared with actual driving performance. Study II reports on the development and psychometric evaluation of a self-report instrument for perceived driver competence - the Self-Efficacy Scale for Driver Competence (SSDC). The findings provides support for construct validity, as the SSDC demonstrated sound psychometric properties and as the internal structure of the SSDC corresponded to the theoretical model used as a basis for instrument development. In study III, the psychometric properties of the SSDC were further examined using an item response theory (IRT) model. The findings confirmed the results indicated by the classical analyses in Study II. Additional information was provided by the IRT analyses, as it was indicated that the scale would benefit from fewer scale points or by putting labels on each scale point. In study IV, Swedish and Finnish candidates’ self-assessment accuracy was examined by comparing candidates’ scores on the SSDC and a similar instrument for self-assessment of driving skill used in Finland, with driving test performance. Unlike previous studies, in which drivers compared their perceived skills to that of the average driver, a relatively large proportion made a realistic assessment of their own skills. In addition, in contrast to previous studies, no gender differences were found. These results were also confirmed in study V, where the results from the Finnish instrument for self-assessment of driving skill were compared with the results from a similar instrument used in the Netherlands. Study VI further examined the construct validity of a revised version of the SSDC, combining qualitative and quantitative sources of evidence. There was a strong relationship between the SSDC and an instrument for self-assessment of driving skills, providing support for convergent validity. No relationship was found between the SSDC and driving test performance. Explanations of the lack of relationship were provided from semi-structured interviews, as they indicated that confidence in performing different tasks in the test are different from being confident of passing the test, and that the candidates are familiar neither with assessing their own skills nor with the requirements for passing the test. In conclusion, the results from this thesis indicated that the choice of methods for assessing perceived driver competence as well as the quality of these methods affect the validity. The results provided support for different aspects of construct validity of the SSDC. Moreover, the findings illustrated the benefits of combining different methods in test validation, as each method contributed information about the validity of the SSDC. The studies in this thesis mainly examined internal and external aspects of construct validity. Future studies should examine procedural validity of the SSDC.

Diagnostic testing is essential to distinguish non-diseased individuals from diseased individuals. More accurate tests lead to improved treatment and thus reduce medical mistakes. The sensitivity and specificity are two important measurements for the diagnostic accuracy of a diagnostic test. When the test results are continuous, it is of interest to construct a confidence interval for the sensitivity at a fixed level of specificity for the test. In this thesis, we propose three empirical likelihood intervals for the sensitivity. Simulation studies are conducted to compare the empirical likelihood based confidence intervals with the existing normal approximation based confidence interval. Our studies show that the new intervals had better coverage probability than the normal approximation based interval in most simulation settings.

Diagnostic tests are central in the field of modern medicine. One of the main factors for interpreting a diagnostic test is the discriminatory accuracy. For a continuous-scale diagnostic test, the area under the receiver operating characteristic (ROC) curve, AUC, is a useful one-number summary index for the diagnostic accuracy of the test. When only a particular region of the ROC curve would be of interest, the partial AUC (pAUC) is a more appropriate index for the diagnostic accuracy. In this thesis, we develop seven confidence intervals for the pAUC under the semi-parametric models for the diseased and non-diseased populations by using the normal approximation, bootstrap and empirical likelihood methods. In addition, we conduct simulation studies to compare the finite sample performance of the proposed confidence intervals for the pAUC. A real example is also used to illustrate the application of the recommended intervals.

In this thesis, we study two independent samples under right censoring. Using a smoothed empirical likelihood method, we investigate the difference of quantiles in the two samples and construct the pointwise confidence intervals from it as well. The empirical log-likelihood ratio is proposed and its asymptotic limit is shown as a chi-squared distribution. In the simulation studies, in terms of coverage accuracy and average length of confidence intervals, we compare the empirical likelihood and the normal approximation method. It is concluded that the empirical likelihood method has a better performance. At last, a real clinical trial data is used for the purpose of illustration. Numerical examples to illustrate the efficacy of the method are presented.

U-statistics generalizes the concept of mean of independent identically distributed (i.i.d.) random variables and is widely utilized in many estimating and testing problems. The standard empirical likelihood (EL) for U-statistics is computationally expensive because of its onlinear constraint. The jackknife empirical likelihood method largely relieves computation burden by circumventing the construction of the nonlinear constraint. In this thesis, we adopt a new jackknife empirical likelihood method to make inference for the general volume under the ROC surface (VUS), which is one typical kind of U-statistics. Monte Carlo simulations are conducted to show that the EL confidence intervals perform well in terms of the coverage probability and average length for various sample sizes.

Bakgrund Svensk media uppmärksammade i början av 2000-talet brott mot livsmedelslagstiftningen inom både Sverige och andra länder i Europeiska unionen. Köttbedrägerier och fusk med ursprungsmärkning hade förekommit. Syfte Studiens syfte var att undersöka konsumenters läsande av och förtroende för obligatorisk livsmedelsinformation, att se om det fanns skillnader beroende på kön eller grad av utbildning, samt om det fanns samband mellan läsfrekvens och förtroende för informationen. Metod En enkät utformades i Google Documents och delades ut i Sverige hösten 2013 via forumet Facebook. Totalt samlades 159 enkäter in och analyserades i SPSS 21.0, med p=<0,05. Resultat Av den studerade livsmedelsinformationen läste deltagarna beteckning och bäst före-datum/sista förbrukningsdag mest frekvent. Förtroendet för obligatorisk livsmedelsinformation var överlag högt men signifikanta skillnader sågs varken beroende på kön eller utbildningsnivå. Kvinnor läste allergimärkning och ursprungsmärkning signifikant oftare än män. Högutbildade läste mängddeklaration signifikant oftare och förvaringsanvisning signifikant mer sällan än lågutbildade. Det fanns en signifikant positiv korrelation mellan hur ofta informanterna läste och hade förtroende för bäst före-datum/sista förbrukningsdag. Slutsats Den obligatoriska livsmedelsinformationen lästes med varierande frekvens men totalt sett oftare av kvinnorna än av männen. Skandalerna som uppmärksammats i media har inte orsakat lågt förtroende för informationen. För att bedöma om skandalerna har påverkat förtroendet i någon riktning bör studier som jämför situationen före med efter de skett göras. Huruvida läsfrekvens och förtroende för informationen har samband bör även det studeras ytterligare. / Background In the early 2000s the Swedish media reported violations of food law regulations in Sweden as well as in other countries in the European Union. Meat fraud had been observed and country of origin labeling manipulated. Objective The purpose of the study was to investigate consumers reading of and confidence in mandatory food information, to find out if there were differences according to gender or level of education. Furthermore the intention was to investigate if there were correlations between frequency of reading and having confidence in the information. Method A questionnaire was designed in Google Documents and handed out via the Facebook community in Sweden in the autumn of 2013. In total 159 questionnaires was collected and analyzed in SPSS 21.0 with p=<0,05. Results The participants read the name under which a product is sold and the date of minimum durability most frequently. Confidence in the mandatory food information was generally high but there were no significant differences according to gender or level of education. Women read allergy labeling and country of origin labeling significantly more often than men. Highly educated people read quantity declaration significantly more often and storage condition significantly less often than people at a lower level of education. There was a significant positive correlation between how often the participants read and had trust in the date of minimum durability.  Conclusion The mandatory food information was read with varying frequency but overall more often by women than men. The scandals reported in the media have not caused low trust in the information. In order to assess whether the scandals have affected the trust in any direction studies should be made comparing the situation before with after they occurred. Whether frequency in reading is correlated with trust in the information should also be further studied.

Background: Communication allows people to gain understanding of themselves and their surroundings, which is a prerequisite for good health. The nurse may in her communication help patients develop a feeling that they are not alone in their situation. If the patients cannot express themselves and make themselves understood, it can lead the patients to feel left out which emphasizes the suffering at having aphasia. Aim: The aim of this study was to identify the components which affect nurse’s communication with patients with aphasia. Analysis method: A literature review was made based on eleven scientific articles in which similarities were pointed out. Results: The result of this study is presented in three main categories: Time, Environment and Strategies. Eighth subcategory emerged: Knowledge and patient under Time; Physical and psychosocial under Environment; and Verbal, Nonverbal, Augmentative and Alternative Communication (AAC) and Individual Care under Strategies. Conclusion: This study reveals how nurses can provide the opportunity for patients to increase self-confidence. The result suggests that a person-centered communication care plan as a basic instrument to facilitate patient and caregiver interaction is needed.

Pasitikėjimas savimi - požiūris, kuris leidžia asmenims turėti teigiamą realistinę nuomonę apie save ir savo padėtį. Paauglių pasitikėjimas savo sugebėjimais, bendrąja prasme, turi kontroliuoti savo gyvenimą. Mokykla yra vieta, kur paaugliai turi plėtoti savo identitetą, vertybes ir savigarbą. Psichologai ir pedagogai teigia, kad savo verte ir pasitikėjimu savimi, priklauso nuo jų sugebėjimų ir individualių savybių. / Self - confidence is an attitude which allows individuals to have positive yet realistic views of themselves and their situations. Self - confident teenagers trust their own abilities, have a general sense of control in their lives. School is the place where teenagers develop their own identities, values and self - esteem. Psychologists and pedagogues notice that self - value and self-confidence depend on their abilities and individual features.

Determining if an athlete, who has had Anterior Cruciate Ligament (ACL) surgery, is ready to return to sport is a difficult clinical decision, partially due to the lack of standardized evaluation protocols. Since there is a risk of re-injury post-surgery, medical teams need to be cautious. However, athletes who are perceived to be ready to return to sport do not necessarily do so. Some leave sport altogether while others return to a lower competition level. As psychological thoughts and emotions are relevant to athletes’ injury experiences, a psychological component, such as sport confidence, needs to be thoughtfully considered during the return to sport process. Our objectives were to develop the relationship between drop vertical jump (DVJ) performance and physical attributes in young healthy adults and to then apply this relationship to ACL participants. Another objective was to see if the relationship is improved by including confidence (determined from a survey). It was hypothesized that including confidence will predict the ACL participants’ DVJ performance more precisely. Thirty-five participants were in the control group with thirteen participants in the ACL group. All were recreationally active and all had the following anthropometric and performance measurements recorded: height, weight, calf and thigh girth, knee angle, leg dominance, percent body fat, skeletal muscle mass, anaerobic power, balance, and drop vertical jump height. The ACL group also completed a confidence survey. Regression analyses were performed. The results showed that anaerobic power and relative skeletal muscle mass were significant predictors of DVJ performance; however, DVJ performance could not be predicted precisely. The analysis was also carried out by gender. No significant predictors for male’s DVJ performance were found while the significant predictors for female’s DVJ performance were weight, power and knee extension angle. Once again, DVJ performance could not be precisely predicted. On the other hand, results showed that power could be more precisely predicted by body weight than could DVJ performance. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2009-08-19 16:08:52.13