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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Generalising from Case Studies

Wikfeldt, Emma January 2016 (has links)
The generalisability of case study findings is heavily criticised in the scientific community. This study attempts to answer to what extent generalisation is possible, through a literature review. Resources were collected by searching in databases and in reference lists. A presentation of arguments from both sides will follow, finding that generalisation is possible to almost the same extent as quantitative research, if done correctly and carefully, with great concern and accuracy.
2

A Comparison Study on Violent Video Games: Explained by the Gamers Themselves

Kneifer, Christopher John 08 July 2014 (has links)
This qualitative focus groups analysis examines the harmful effects of violent video games on emotions and behavior by comparing violent video game player's responses to that of non-violent video game players of the same age group. Research on the effects of video games has been done since the 70s, yet more research is needed to better understand the potentially harmful emotional and behavioral effects of playing violent games, especially from the gamers' perspectives. This thesis presents a qualitative analysis of data obtained from focus group sessions among undergraduate college students. Results of the analysis supports the presence as well as absence of violent video game effects, according to violent and non-violent video gamers' personal experiences and in their own words.
3

Investigating the Effectiveness of Physical Activity Interventions for Older Adults

Antikainen, Iina E 11 August 2011 (has links)
Regular physical activity can help prevent chronic conditions and it is positively linked to health-related quality of life (United States Department of Health and Human Services [USDHHS], 2000). Unfortunately, many older adults do not engage in leisure time activity (USDHHS, 2000); making it important to design and test physical activity interventions for this population. The purpose of this dissertation was to review the external validity of theory-based physical activity interventions and to examine the efficacy of a mail-based physical activity intervention. The review included 54 theory-based interventions and overall the studies focused on internal rather than external validity. The hypotheses of the experimental study were that the psychological mediators and physical activity participation would significantly increase among the treatment group as compared to the control group, and that the changes in the mediators would be related to the changes in activity levels. The intervention included 4 weekly stage-matched packages targeting population specific physical activity beliefs (Antikainen et al., 2009) and weekly phone calls to reassess stages of change. Physical activity participation, stages of change, and theory of planned behavior constructs were assessed at baseline and follow-up. Differences in activity levels and theory-based constructs were assessed with repeated measures mixed analysis of variance. Stage of change progression was examined with chi-square analysis. Measured variable path analysis was used to determine associations between the theory constructs, stages of change, and physical activity participation. The participants were 55 older adults, ages 54 to 96 years. Most of the participants were female, Black, and reported low levels of education and income. The treatment group reported statistically significantly greater physical activity after the intervention than the control group that reported lower levels of activity at follow-up. Although not statistically significant, there was a trend in SOC progression after the intervention in the treatment group. Finally, the integrated model was found to have a good fit at follow-up and perceived behavioral control emerged as a significant predictor of physical activity. This research provides important information for the design of physical activity interventions based upon the integrated framework for translation to community-based organizations.
4

Improving predictive validity of choice-based conjoint models

Natter, Martin, Feurstein, Markus January 2000 (has links) (PDF)
Up to date, it is unclear how Choice-Based Conjoint (CBC) models perform in terms of forecasting (external) real world aggregate shop data. In this contribution, we measure the performance of a Latent Class CBC model - not with an experimental holdout sample - but with aggregate real world scanning data. We find that the CBC model does not accurately predict real world market shares. In order to improve the forecasting performance, we propose a correction scheme based on external scanner data. Our analysis based on 8 brands shows that the use of the proposed correction vector improves the performance measure considerably. (author's abstract) / Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
5

Evaluating the long-term sustainability of the ENCOURAGE (ENhancing primary care COUnseling and Referrals to community-based physical Activity opportunities for sustained lifestyle chanGE) project utilizing methods to determine external validity

Chapman, Soyun 15 February 2017 (has links)
Primary care based physical activity interventions have been shown to be efficacious when delivered under controlled research conditions, over the short-term. However, few studies have evaluated the long-term sustainability of these health interventions utilizing methods to determine external validity. Our own research group conducted the ENCOURAGE project, which enabled previously sedentary individuals (Age, 51 ± 1 years; BMI, 35.2 ± 0.8) to increase their total physical activity by 104 minutes a week. Although the ENCOURAGE project has now ended, a number of stakeholders are utilizing project outcomes to inform best practice within their respective organizations. The purpose of this thesis project was to use the RE-AIM framework to evaluate the external validity of the ENCOURAGE project, and to describe the stakeholders’ perceptions regarding the long-term sustainability of the project utilizing methods from a stakeholder analysis assessment. Results from the RE-AIM evaluation suggest that three of the five dimensions of the framework were met, notably: Reach, Adoption and Implementation. Therefore, the ENCOURAGE project generated a moderate level of public health impact. Semi-structured interviews were conducted with eight key stakeholders who were involved with the design, development or implementation of the project. Although the ENCOURAGE project was not adopted into the health care system, it left notable implications on the recognition of physical activity in primary care, and the delivery of physical activity services in primary care. Furthermore, the project was able to influence the primary care providers’ perceptions about physical activity, community-based programing and health policy. These positive changes observed at the individual, organizational and system-level are sustainable over the long-term. / February 2017
6

Correcting for CBC model bias. A hybrid scanner data - conjoint model.

Natter, Martin, Feurstein, Markus January 2001 (has links) (PDF)
Choice-Based Conjoint (CBC) models are often used for pricing decisions, especially when scanner data models cannot be applied. Up to date, it is unclear how Choice-Based Conjoint (CBC) models perform in terms of forecasting real-world shop data. In this contribution, we measure the performance of a Latent Class CBC model not by means of an experimental hold-out sample but via aggregate scanner data. We find that the CBC model does not accurately predict real-world market shares, thus leading to wrong pricing decisions. In order to improve its forecasting performance, we propose a correction scheme based on scanner data. Our empirical analysis shows that the hybrid method improves the performance measures considerably. (author's abstract) / Series: Report Series SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
7

Individual level or segmentation based market simulation?

Natter, Martin, Feurstein, Markus January 1999 (has links) (PDF)
In many studies, choice based conjoint analysis is used to build a market simulator to develop marketing strategies; i.e., shares-of-preference are taken as market share forecasts. However, conjoint data are collected in interview situations, which may differ considerably from real shopping behavior. In this paper, we test the internal and external validity of four commercial choice based conjoint pricing studies including a total of 43 brands. We use conjoint and sales data to assess the relative performance of two modern approaches to estimate conjoint parameters: the segmentation based Latent Class model and the individual level Hierarchical Bayes approach. Our paper confirms previous results of the internal superiority of the Hierarchical Bayes approach. The main result of our investigation is that internal validity does not predict external validity and that Latent Class shows the same real world performance as Hierarchical Bayes. Both models show an average error of 4.2% in market share level prediction and a correlation of 69% between conjoint forecasts and real market shares. (author's abstract) / Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"
8

The external validity of South African substance use contextual risk instrument: predictive validity

Bester, Kyle John January 2017 (has links)
Magister Artium (Psychology) - MA(Psych) / The purpose of the present study was to gather further external validity evidence towards the validity argument for an instrument designed to measure individual and contextual factors associated with adolescent substance use in low socio-economic status communities in the Western Cape, South Africa. The South African Substance Use Contextual Risk Instrument (SASUCRI) measures adolescents’ subjective experiences of their own psycho-social and their communities’ functioning. The present study uses secondary data analysis in order to further evaluate its external validity. Both content and structural evidence for the instrument has been gathered in the larger study in which the present study is located. Validity theory was used as the theoretical framework for the gathering of the different types of evidence in support of the validity argument for this instrument. The study employed non-probability purposive sampling to select schools from three education districts from which twenty-six schools were selected where the sample total was N=1959. English and Afrikaans versions of the instrument were administered to English- and Afrikaans home language, school-going adolescents, aged 12 to 21 years. All ethical standards were maintained throughout the research process. External evidence procedures were conducted using Discriminant Function Analysis (DFA) to evaluate the extent to which the instrument could discriminate between substance using and non-using adolescents. The DFA revealed that nine SASUCRI sub-scales totals can act as significant predictors to substance use among adolescents based on the predictive validity of sub-scales.
9

Evaluation of skill maintenance, performance factors, and external validity in a behavioral parent training program.

Scherbarth, Andrew J. 08 1900 (has links)
Child maltreatment affects 900 thousand children in the U.S. every year and impacts all areas of daily functioning. Behavioral parent training (BPT) programs have effectively taught parenting and demonstrated externally valid outcomes (i.e., lower recidivism rates). Skill maintenance assessments for BPTs have mixed results. The Behavior Management and Parenting Services (BMAPS) program has shown effective skill training for court-mandated families. This study assessed skill maintenance and performance factors that may have impaired parents using an ABAB single-case research design in Phase 1 & external validity with a survey in Phase 2. Results for Phase 1 found that most BMAPS parents acquired all parenting tools to criteria, dropped below criteria at the 3 month probe, then fully demonstrated their regained skills after a brief review. Psychological and classroom factors do not appear to have systematically influenced performance at any time, although homework completion was associated with better scores at the end of class. Phase 2 results found a 91% reunification rate and a 0% recidivism rate over 1-3 years. All limitations aside, it appears that the BMAPS program is able to effectively train skills to criteria and these skills can be sustained with a booster session. The vast majority of parents we contacted were reunified with their children and none were involved with additional charges of child maltreatment.
10

Effects Of Voluntary Control On Performance Response Under Stress.

Morris, Christina Shawn 01 January 2004 (has links)
Recent stressful environments within military and non-military domains are producing a new challenge for the lab-based study of stress on task performance, one that requires knowledge of underlying cognitive-motivational and goal orientation factors. Results of recent stress on task performance research traditionally employ metaphorical explanations (i.e., resource theory) in order to rapidly apply stimulus-response outcomes to the real world counterparts. This dissertation provides an alternative perspective about these metaphorical, or black box, interpretations and reveals how they may be confounded with respect to the intended real world counterpart. To examine how voluntary human control can influence traditional stress/no-stress research findings, traditional as well as exploratory paradigms were presented. Both noise and time pressure conditions produced significant differences between experimental and control groups on visual discrimination. However, when analogous cash payment-contingency conditions were employed, the traditional stress/no-stress findings were not evident. In addition, a second experiment revealed that this trend of differences (and non-differences) held consistently over 30 minutes of interrupted task performance time. This study indicates the importance of developing more diagnostic measures that include assessments of how the differences between participants' and the generalized operators' goals and motivations may alter results in stressful task environments.

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