Experimental-Design-实验设计

1、,0,1,7,Experimental design,2,目录 contents,1,2,3,4,Definition,1,6,7,8,5,Significance,9,Components,Types,Compare,Conceptual framework,Application,Summary,Case discussion,Definition of experimental design,1,Experimental design is a detailed experiment design which is done before the experiment, it chang

2、es one or more process variables to observe the response variable changes, it is a procedure for obtain the research data, and gain yield valid and objective conclusion (Winer, 1971). Experimental design is a research design that eliminates all factors that influence outcome except for the cause bei

3、ng studied (independent variable), all other factors are controlled by randomization, investigator-controlled manipulation of the independent variable, and control of the study situation by the investigator, including the use of control groups (Medical dictionary).,2,Significance of experimental des

4、ign,Discussion: (1 min) The significance of experimental design You can divide into four groups freely, and choose one to two representative(s) to anwer.,2.1 The design of any experiment is of utmost importance because it has the power to be the most rigid type of research (most precise/ strict). Ex

5、perimental design is the most rigorous of all research designs. 2.2 Be used to exploring the effectiveness of an intervention or treatment, how effective the intervention is? In other words, the experimental design gives evidence that whether one variable can cause change to another variable or not.

6、 2.3 The scientific experiment design can use less test times to achieve the expected test target (get twice the result with half the effort).,2.4 Experimental design is the main step in conducting a research, a clear definition in details of the experiment makes the desired statistical analyses pos

7、sible, and almost always improves the usefulness of the results (Barker, 2016). 2.5 Experimental design is the process of planning a study to meet specified objectives, it is very important to ensure that the right type of data and a sufficient sample size and power are available to answer the resea

8、rch questions of interest as clearly and efficiently as possible (Barker, 2016).,Significance of experimental design,3,Components of experimental design,3.3 Study groups (Participants),3.2 Constants,3.1 Variables,3.4 Intervention/Treatment,3.5 Outcome/Results,3.6 Instrument,3.1 Variables IV: Indepen

9、dent/Experimental variable is the factor(s) that is purposefully changed or manipulated by the experimenter. DV: Dependent/Response variable is the factor(s) that response to the change or in other words, respond to the IV (be used to measure the outcome/result). EV: Extraneous variables are not in

10、the study but can affect the study variables and their relationship.,Components of experimental design,3.2 Constants Constants are the factors that remain the same or are purposefully kept the same during an experiment. 3.3 Study groups (Participants) E: Experimental group is manipulated by receivin

11、g the treatment C: Control group is not manipulated,Components of experimental design,3.4 Intervention/Treatment X/T: The factor that is being manipulated is typically referred to as the treatment or intervention. 3.5 Outcomes/Results O: Pretest and Post-test (can be more than once) 3.6 Instrument A

12、 device or scale for recording, measuring, or controlling, especially such a device functioning as part of a control system. It usually be used to measure the outcome or result in experimental design.,Components of experimental design,Types of experimental design,4,Question: (1 min) 1. Do you konw h

13、ow many types of experimental design ? 2. What is the difference(s) between/among them ? The same, you can divide into four groups freely, and choose one to two representative(3) to anwer.,Typs of experimental design,4.1 Pre-experimental design,4.2 True experimental design,4.3 Quasi-experimental des

14、ign,(Campbell Stanley, 1963),Types of experimental design,4.1 Pre-experimental design Pre-experimental designs are so named because they follow basic experimental steps but fail to include a control group. In other words, a single group is often studied but no comparison between an equivalent non-tr

15、eatment group is made. The characteristics of pre-experimental designs are: Manipulation of independent variables Limited control over the extraneous variables No randomization and control group,Types of experimental design,4.1 Pre-experimental design - Types,Types of experimental design,4.2 True ex

16、perimental design - Characteristic Random selection of participants and the random assignment of the participants to groups in the study. Exposure of some of the subjects to the one treatment (experimental group); and no exposure of some of the remaining subjects (control group),Types of experimenta

17、l design,4.2 True experimental design - Characteristic Causality between the IV and the DV is examined under highly controlled condition (Kerlinger Lee, 2000). So it is considered the most powerful quantitative method because of rigorous control of variables and complete control over the extraneous

18、variables. (confidently determined that effect on the DV is directly due to the manipulation of the IV),Types of experimental design,4.2 True experimental design - Types (1) Without comparison group Post-test only comparison group design (2) With comparison group - With repeated measures Repeated me

19、asures design - Without repeated measures Pretest/post-test comparison or control group design (*) Randomized clinical trials (*) Randomized block design (*) Solomon four-group design Factorial designs Multivariate designs Nested designs,Types of experimental design,(*),(*),(*),4.3 Quasi-experimenta

20、l designs Quasi-experimental designs are conducted to determine the effect of a treatment or independent variable on the dependent variables, it is consistent with true experimental design at this point, but there is a little bit different: Lack the control of the design, sample, or setting that mig

21、ht be used in an true experimental design (in situation in which complete control is not possible, or not randomly assigned) (Grove, and no exposure of some of the remaining subjects (control group),Causality between the IV and the DV is examined under highly controlled condition. Most powerful quan

22、titative method because of rigorous control of variables,Lack the control of the design, sample, or setting that might be used in an true experimental design (in situation in which complete control is not possible, or not randomly assigned) (Grove, ,Quasi-experimental design is applied when: The res

23、earchers want to test the accuracy of a theory by determining if the independent variable(s) causes an effect on the dependent variable Lack random allocation of groups Lack of manipulations.,If you want to study the effect of maternal alcohol use when the mother is pregnant. Which experimental desi

24、gn(true experimental design or quasi-experimental design) you will use? and why?,Discussion,Experimental study of “the effects of behavioral interventions on disruptive behavior and affect in demented nursing home residents.” Which experimental design(true experimental design or quasi-experimental d

25、esign) the researcher used? and why?,Discussion,The researcher uses quasi-experimental design to exam the effect of maternal alcohol to the embryos (one group). Because the researcher can not develop a true experimental design, because alcohol does harm embryos and it is highly illegal because of th

26、e possible harm the study might do to the embryos. So the researcher can not randomly assign the mother to experimental group or control group.,the study had three treatment groups (activities of daily living, psychosocial activity, and a combination) and two control groups (placebo and no intervent

27、ion). All of the residents are random to groups. Nursing assistants hired specifically for this study enacted the intervention under the direction of masters prepared gerontological clinical nurse specialist. Nursing assistants employed at nursing homes recorded the occurrence of disruptive behavior

28、s. Raters analyzed videotapes filmed during the study o determine the interventions influence on affect.,7,1. Control group and experimental group,2.ramdon,3. Manipulation the variables,Apply experimental design: 7.1 Indicators,7.2.1 Validity Experimental validity refers to the manners in which vari

29、ables influence both the results of the research and the generalizability of the population. It is divided down into two groups: (1)Internal Validity and (2)External Validity. 7.2.2 Ethic,7.2.1 Validity (1) Internal Validity: Internal validity refers to a studys ability to determine if a causal rela

30、tionship exists between one or more independent variables and one or more dependent variables. (2) External Validity: External validity refers to the ability to generalize the findings of the study.,Historical factors,Selection,Regression toward the mean,Attrition,Apply experimental design: consider

31、ations,Experimenter effect,Instrumentation,Time to test,Maturation,Demand Characteristics,Experimental Procedures,Multiple Treatment Interference,Apply experimental design: considerations,If a researcher wants to study the effect of maternal alcohol use when the mother is pregnant.” by using questio

32、ners to exam the factors that influence the mothers behavior. Question : which factors will influence the validity of results? A age E given the same test several times B education level F attrition C experience events G mothers expect D environmental H the time to give questioners,Discussion,7.2.2

33、Ethic In experimental research, ethical standards prevent against such things as the fabrication or falsifying of data and therefore, promote the pursuit of knowledge and truth which is the primary goal of research. In quasi-experimental research, ethical principles are primarily centered on protect

34、ing research participants and the guiding foundation of “do no harm”. The core ethical principles are Respect for persons; Beneficence; Justice; Respect for communities.,8,Summary,- Case study - Analysis, - Comparation - Consideration,Case Discussion,9,The researchers would like to conduct a study a

35、bout the effect of a dietary self-management programme for community-dwelling older adults in urban and rural areas. The duration of dietary self-management programme is 12 weeks. The level of nutritional status, nutritional self-efficacy and health locus of control can be seen as the outcomes of th

36、is programme, and all of them can be measured by using questionnaires. Now, if you were the researcher, which research designs that you will choose?,posttest only one group,Posttest-only control-group design,Pretest/post-test comparison or control group design,Solomon four-group design,Intervention(

37、 independent variable),Participants,Three dependent variables,From the introduction, we can see there is an intervention of dietary self-management programme in this study. The programme and usual care can be seen as the independent variables, and the level of nutritional status, nutritional self-ef

38、ficacy and health locus of control can be seen as the three dependent variables. Besides, the researchers want to determine the effect of the independent variable(s) causes effects on the dependent variable(s) according to control the condition(s)/ variable(s) and using statistic methods. In this si

39、tuation we can choose an experimental design.,Discussion - Analysis,True experimental designs are considered the most powerful quantitative method because of rigorous control of variables. And in this study, we can randomize the older people into two groups (control and experiment group), and contro

40、l the independent variable (dietary self-management programme, and usual care). Finally, manipulate the extraneous variables, like the age, gender. So the true experimental design can be used here.,Discussion - Analysis,For many true experimental designs, pretest-posttest control designs are the pre

41、ferred method to compare participant groups and measure the degree of change occurring as a result of treatments or interventions. In this study, we already can obey to the three characteristics. And then, the three variables in the control group and experimental group will be measured when the olde

42、r people enter and finish this study. So the true-experimental pretest-posttest control group may be the suitable design here (figure 1).,Discussion - Analysis,R: Random E: Experimental group C: Control group,X: dietary self-management programme O1: Refers to the measurement of three dependent varia

43、bles in experimental and control group when the older people particpante in this study O2: Refers to the measurement of three dependent variables in experimental and control group when the older people received the intervention or usual care, respectively.,Discussion - Analysis,Historical factor,Experiment procedure,Attrition,Is there any factor that can influence the validit