在觀察性研究或非隨機試驗研究中，欲探討因果效應時，研究者需要重新對觀察性研究進行設計，設計目的在於重新建立一個隨機指派受試者的機制，使其得以近似一個隨機試驗研究，這樣的研究一般稱為「類隨機試驗研究」(quasi-randomized-experiments)。 傾向分數分析即為一種設計觀察性研究的方法，在不牽涉到反應變數結果之下進行設計。本文於一個病例對照研究(case-control study)中使用傾向分數進行配對接著再進一步估計處理效果，傾向分數配對是可降低觀察性研究中的選擇性偏誤的方法，透過配對可減少實驗組與對照組間的系統性差異，使研究群體在所觀察到的控制變數分配達到相似，進而得到處理效果(treatment effect)的不偏估計，為近年廣受流行病學、經濟學以及社會學領域使用的方法之一。傾向分數本身為一個條件機率，定義為研究受試者在其所觀察到的控制變數之下，接受某處理或被指派至某特定群體的機率，估計傾向分數最常見的方法為羅吉斯迴歸。 此外，自1970年代起，配對方法(matching method)開始被使用來選取合適的實驗組與對照組並進行兩群體的比較，其中「確切配對」屬於最常使用的配對方法，過去文獻中經常可見各種配對方法的結合使用，因此，本文電腦模擬研究部份，欲比較四種情境之下「傾向分數配對」與「確切配對」結合使用的效果，分別以偏誤降低比例、信賴區間覆蓋率、均方誤衡量兩種配對方法結合使用的適合情境。結果顯示若對「與處理指派中度相關的變數」且「與反應變數高度相關的變數」，其效果最為明顯。根據結果，我們總結認為「確切配對與傾向分數配對合併使用」確實會有較好的表現，但表現的好壞也取決於確切配對的變數。實證研究部份，探討家庭結構對青少年偏差行為之影響，欲了解來自非完整家庭之青少年是否較來自完整家庭之青少年更有容易出現偏差行為。 / In observational or nonrandomized studies, treatments are not randomly assigned so that baseline differences between treated and control groups are typically observed. Without properly executed, the differences would bias the treatment effect estimates. There has been a long history of using matching to eliminate confounder bias, and inferences are made based on the matched observations. The theoretical basis for matching has been developed since 1970, and among those matching methods commonly in use, the exact matching is probably the most popular one. On the other hand, introduced by Rosenbuam and Rubin in 1983, propensity scores, the conditional probability of being exposed or treated given the observed covariates, has been a welcome alternative used to adjust for baseline differences between study groups of late. Instead of matching a treated with an untreated subject by their covariates, subjects in both treated and control groups are matched by their propensity scores. In this study, we explore the benefits of using propensity score matching together with the exact matching for adjusting for baseline differences through Monte Carlo simulations. An empirical study is also be provided for illustration.

Professionals in education continue to explore technology as a way to instruct young students, and there is an accompanying belief that this technology can make an educational and academic difference. Despite the high percentage of young students in classrooms using technology, the impact of this technology on the early literacy skills of young children remains largely unknown. Guided by Vygotsky’s social learning theory, this study reports a 24-week investigation on whether regular use of Istation®, an integrated learning system used by approximately 3,000,000 students in the United States, had an effect on the early literacy achievement of children in twelve kindergarten classrooms. A mixed-method, quasi-experimental design was constructed using propensity scores. Also investigated were the effects of the level of teacher literacy support on early literacy achievement and the interaction between Istation® use and the level of teacher literacy support. A descriptive discriminant analysis was performed to determine the main effect of Istation®. The level of teacher support and the interaction effect was then tested using a multivariate between-subject analysis. Results indicated that Istation® did have a statistically significant effect on the early literacy skills of the 72 kindergarten students studied and was able to explain 17.7% of the variance in group differences. Hearing and recording sounds and letter sound knowledge were the main contributors to group differences. Teacher literacy support and the interaction between teacher support and Istation were not significant. This study considers the relationship between technology and early literacy and concludes that Istation® can serve as a more knowledgeable other as students develop some early literacy skills; however, teachers are still needed to provide complete literacy instruction for young students.

Objective: To determine whether continuity of care (COC) reduces emergency department (ED) visits and/or readmission in adolescents with psychiatric disorders. Methods: A retrospective cohort of adolescents discharged with psychiatric disorder between April 1, 2002 and March 1, 2004 was identified using hospital administrative databases. Good COC was defined as at least one aftercare contact in 30 days. Confounding by patient characteristics was adjusted for by propensity-score-matching of good and poor COC adolescents. Cox PH was used to analyze time to outcome. Results: 48.77% of adolescents had good COC. 38.39% of adolescents had ED visit or readmission in the year post-discharge. Good COC increased risk of readmission (HR = 1.38 (1.14 – 1.66)), but not of ED visits (HR = 1.14 (0.95 – 1.37)). Conclusions: COC increased risk of readmission by 38% but did not increase risk of ED visits. These findings are contextualized. Implications to adolescent mental health service delivery are discussed.

Objective: To determine whether continuity of care (COC) reduces emergency department (ED) visits and/or readmission in adolescents with psychiatric disorders. Methods: A retrospective cohort of adolescents discharged with psychiatric disorder between April 1, 2002 and March 1, 2004 was identified using hospital administrative databases. Good COC was defined as at least one aftercare contact in 30 days. Confounding by patient characteristics was adjusted for by propensity-score-matching of good and poor COC adolescents. Cox PH was used to analyze time to outcome. Results: 48.77% of adolescents had good COC. 38.39% of adolescents had ED visit or readmission in the year post-discharge. Good COC increased risk of readmission (HR = 1.38 (1.14 – 1.66)), but not of ED visits (HR = 1.14 (0.95 – 1.37)). Conclusions: COC increased risk of readmission by 38% but did not increase risk of ED visits. These findings are contextualized. Implications to adolescent mental health service delivery are discussed.