社会项目评估

2013年社会工作者考试全攻略
每日一练历年真题模拟测试章节知识点
21 1. 实验设计和准实验设计|区别在于：是否存在控制z在自然状态下的研究，被观察对象按自己的轨迹发生z在实验研究中，事件被制造出来以便进行研究z如：对服务对象人为分组并采用不用的干预/服务方法，就是实验研究|在社会工作中，自然状态下的研究多用于对现象的一个时点的考察。

z如考察一个机构案主的人口学特征z如研究婚姻状态和健康的关系z如机构对服务传递的影响|实验研究多为干预研究，多用于评估考察治疗/服务的效果|实验设计就是通过改变现象研究改变的效果|有助于揭示因果关系zTo establish causality between independent variable (SW intervention/control) and dependent variable (problem or outcome) zExplanatory 分类：Field experiment and laboratory experiment zField experiment: in natural settings, usually zLaboratory experiment: in lab, rare in social work |(True) experiment and quasi-experiment: z
Experiment: designs with equivalent groups produced by random assignment zQuasi-experiment: lacking equivalent groups
•quasi-experimental designs for evaluating programs and practice when practical
constraints in agencies make it impossible to conduct experiments •If participants are placed in groups using some other method such as selecting natural groupings (a classroom or community) 2. Pre-experimental designs |Pre-Experimental Designs：|(1) One-shot case (group) study |只对因变量进行干预后的一次测量，没有说明相关关系|虽说明了时间先后，但不能说明因变量变化，不能排除任何其它原因解释|只能通过直觉判断因变量变化情况|(2) One group pretest-posttest design |比较前后测值|说明了相关性和时间先后，但不能排除自变量以外的其它解释，如：history, maturation, testing, and statistical regression | 如测量社会工作学生在入学时和毕业时对贫困问题重要性的认识。

其它解释？| (3) posttest only design with nonequivalent groups X O O1 X O2X O O
22 |比较两组后测值|实际工作中常发生的情况：来不及前测，也无法分等价组|无法排除：如selection biases |以上三种方案，internal validity都不高|但它们也有实际价值，可用于探索或描述性研究|实验设计和准实验设计的internal validity要高于pre-experimental designs 3. 实验设计类型|May not be feasible in real social work setting but can be done in some agency settings |Essential components of experiments: z1) randomly assigning individuals to experimental and control groups z可按抛硬币、随机数码表等方式进行；人数越多，随机分配更有效•例如：申请服务的人和未申请服务的人不算等价组，在申请服务的人中随机分组才可能是等价组z如果没有干预，这两组会一样z虽然无法确保实验组和控制组在所有方面都一样或面临同样的发展过程，但是
随
机分组可帮助实现减少实验组和控制组的差异。

z不同于Random sampling (pertains to generalizability) zRandomization or random assignment旨在提高internal validity, 不寻求样本对总体的代表性，而是重在减少实验组和控制组的差异z2) introducing the independent variable (a program or intervention) to experimental group while withholding it from the control group •Multi-group: 2 or more z3) comparing the amount of experimental and control group change on the dependent variable |再次强调：Key element is random assignment of participants to control or comparison groups zSymbol: R = random assignment zi.e., each participant has an equal opportunity to be assigned to each group, AND every possible combination of participants has an equal opportunity to be assigned to each group |类型1：
classic experimental design or pretest-posttest control group design |Change in scores compared |古典设计要素：z前后测R E O1 X O2 C O1 O2
23 z 实验组和控制组z随机分配|古典设计zCan control: selection, history, testing, instability zCan control IF groups are equivalent: maturation, statistical regression zCan control IF equal numbers & types of dropouts: mortality zDepends on data-collection procedures: instrumentation zCannot control: nonspecific effects, reactivity |类型2 : Partial Crossover Design
Elements: |Data collection: 3 times |
Control group receives intervention AFTER post-test, then 2nd post-test
|Allows for intervention to be given to all |Partial Crossover Design (with Follow Up) 变形Pre Post F/U F/U R E O X O O O C O O X O O Able to determine intervention’s endurance |类型3：Solomon four-group design |两个实验组，两个控制组|两组有前后测，两组只有后测|复杂，应用少|类型4: Comparative/Contrast/Alternative Groups Design |比较两个可选干预方案|NO knowledge of how groups compare to no intervention |变形：alternative treatment design with pretest |比较三个后测值之间的差异|Same controls in comparing each intervention to no intervention |其它可能设计：R E O X O C O O X O R E O X O E X O C O O C O R E1 O X1 O E2 O X2 OR E1 O X1 O E2 O X2 O C O O R E O X12 O E O X1 O E O X2 O C O O
24 课堂讨论：|请分为三组，讨论实验设计的后三种类型分别可以控制或不可以控制哪些threats to internal validity z第一组：类型2 : Partial Crossover Design z第二组：类型3: 所罗门四组实验z第三组：类型4: Comparative/ Contrast/ Alternative Groups Design 社会工作评估第七讲准实验设计与评估04/06/2011 本次课程内容z准实验设计与评估z在许多社会工作机构中，
控制组经常无法实行z即使实现了控制组，但往往无法实现实验组和控制组间的
随机分配z实验设计的替代方式：准实验设计zNon-equivalent Groups (assignment through other means) 准实验设计和实验设计形式相同z内部有效性：pre-experimental designs <准实验设计<实验设计z有助于说明因果关系z与实验设计相比，更为关心组间差异对结果的影响Elements of quasi-experimental designs: –Pre-test and post-test –Multiple groups with experimental and control group –Non-equivalent groups: Participants assigned to groups by non-random means z形成nonequivalent groups的途径：z(1) use natural groups –Class, town, 居住单位，不同社会工作者的案主，等z(2) assign clients in some systematic or haphazard way –e.g., every other client; –如，whoever has space on caseload, 将案主分配给下一个空闲的社工–接近随机分配，但和随机分配不同(3) the wait-list or overflow approach z先来的案主进入实验组，后来的进入控制组z有可能后来者差异很大，或控制组人数不够(4) time: use a comparable group at a different time ze.g., new clients in March vs. those in April, 今年的案主作为控制组，明年的案主进入实验组z如，
上一届学生作为控制组，当届学生作为实验组
25 z无法控制不同时点的差异z准实验设计示意：zNonequivalent treatment and control group design –Find an existing group that appears similar to the experimental group –研究老人院老人的抑郁情况，假设两栋楼的老人基本情况相同，但一栋楼开始养猫，另一栋楼不允许养。

可考察宠物对抑郁的影响。

–
希望两组前测接近，后测不同
z变形：
z增加多次前测z减少selection, maturation, statistical regression等z如实验组有强烈的改变意图，则即使两组第一次前测相同，那么在第二次前测上也有区别z 若两组在两次前测上都相同，那么后测的区别更有可能是干预引起准实验设计与评估z变形：z在后测后对参照组也实施干预z若参照组干预后的后测与实验组不同，则可能是两组间差异引起不同，也可能是干预效果的问题z若两组干预后效果相同，则可排除组间差异，确认干预效果z变形：增加多个控制组z其它准实验设计示意：zNon-equivalent Contrast or Comparison Groups: zCausality: z(1) Association - outcome varies between groups z(2) Time priority strong –if have pre-test, can show change –Independent variable manipulated z(3) Alternative Explanations 04/09/2011整理。