True experimental research design

True Experimental Research Design

1. True Experimental Research Design Prof. (Mr.) Asoka n R I/C of R & D, KINS, KIIT (DU), BB SR.

2. Outli ne Research design True experimental research design Elements of True experimental research design R andomized controlled trial (RCT) . Phases of RCT Types of True experimental research design

3. Introduction

4. What is Design?

5. A  design  is a plan or system or for the implementation of an activity or process, or the result of that plan or specification in the form of a prototype , product or process.  - Wikipedia

6. What is Research design ?

7. It is a blueprint for conducting a study that maximizes control over factors that could interfere with the validity of the findings. Elements control to the study design include the presence or absence of a treatment, number of groups in the sample, number and timing of measurements to be performed, sampling method, time frame of data collection, planned comparisons, and control of extraneous variables.

8. Research design must contain, a clear statement of the research problem; procedures and techniques to be used for gathering information; The population to be studied; and Methods to be used in processing and analyzing data.

9. One may spilt the overall research design into the following parts: i . The sampling design which deals with the method of selecting items to be observed for the given study; ii. The observational design which relates to the conditions under which the observations are to be made; iii. The statistical design which concerns with the question of how many items are to be observed and how the information and data gathered are to be analyzed; and iv. The operational design , which concerns with the techniques by which the procedures specified in the sampling, statistical and observational designs can be carried out.

10. What is T rue experimental design?

11. True experimental design is  a statistical approach of establishing a cause and effect relationship between different variables . This is one of the most accurate forms of research designs which provides a substantial backing to support the existence of relationships. Examples of true experimental designs are:  pre-test - post-test control group, post-test only control group, and a Solomon four group, six-study design .

12. A true experimental design is characterized by the following properties: True experiments have four elements:  manipulation, control , random assignment, and random selection . Manipulation —the experimenter does something to at least some subjects or something is purposefully changed by the researcher in the environment. Control —the experimenter introduces controls over the experimental situation, including the use of a control group. Randomization —the experimenter assigns subjects to a control or experimental group on a random basis

13. Random selection refers  to how the sample is drawn from the population as a whole , while random assignment refers to how the participants are then assigned to either the experimental or control groups. It is possible to have both random selection and random assignment in an experiment.

14. A research study using a true experimental design is commonly called a randomized controlled trial (RCT) . In hospital and clinic settings , it may be referred to as a “ clinical trial ” and is commonly used in drug trials . An RCT is considered the “ gold standard ” for providing information about cause-and-effect relationships. An individual RCT generates Level II evidence because of reduced bias provided by randomization, control, and manipulation. A well-controlled design using these properties provides more confidence that the intervention will be effective and produce the same results over time.

15. Randomization Randomization, or random assignment , distribution of subjects to either the experimental or the control group on a purely random basis. Randomization may be done individually or by groups . Several procedures are used to randomize subjects to groups, such as a table of random numbers or computer-generated number sequences ( Suresh , 2011). Whatever method is used , it is important that the process be truly random , that it be tamperproof, and that the group assignment is concealed ( kept secret ) .

16. Why randomization? The basic benefits of randomization include Eliminates selection bias . Balances arms with respect to prognostic variables (known and unknown). Forms basis for statistical tests, a basis for an assumption-free statistical test of the equality of treatments.

17. Methods of randomization (1) simple - equivalent to tossing a coin for each subject that enters a trial. The random number generator is generally used. (2) Block - to divide potential patients into m blocks of size 2n, randomize each block such that n patients are allocated to A and n to B. then choose the blocks randomly. (3) Stratified - addresses the need to control and balance the influence of covariates. This method can be used to achieve balance among groups in terms of subjects’ baseline characteristics (covariates). (4) Adaptive - changing the allocation probability according to the progress and position of the study. It may be used to minimize the imbalance between treatment groups as well as to change the allocation probability based on the therapeutic effect. 

18. Blinding Blinding, in research, mentions to a practice where the study population or the stakeholders involved in research are not permitted from knowing certain information or treatment , which may somehow influence the study findings. Blinding (also called masking) is typically used in randomized controlled trials (RCTs).

19. There are basically three different types of blinding used in researches: Single blinding or single-masked : In single blinding, only a single stakeholder i.e. either the participant or the investigator is not informed of the nature of treatment the participant is receiving. A trial is called single-blind if  only one party is blinded .  Usually, the participant is blinded   and is unaware of the treatment they receive. Double-blinding or double-masked : Both study population/participant and data collectors/investigators/researchers are not aware of the kind or nature of the treatment given and who receive the treatment. If  both ‘the participants’ and ‘the study staffs’ are blinded , it is known as a double- blind study.

20. Triple blinding : A clinical trial in which neither the subject nor the person governing treatment nor an individual measuring the response to the treatment is aware of the particular treatment received by the subject is known as triple blind. Triple blinded studies also lengthen blinding to the data specialists . In triple blinding,  the study participant, the data investigator or data collector and the data analyzer- all are blinded. Unblinded or open-label : It is the  exact opposite of blinding, where all the participant, clinicians, data collectors, specialists are well known about the treatment/intervention  they receive.

21. Control Control refers to the process by which the investigator holds certain conditions constant to limit bias that could influence the dependent variable(s) / effort by the researcher to remove the influence of any extraneous, confounding variable . Control is acquired by manipulating the independent variable, by randomly assigning subjects to a group, by using a control group, and by preparing intervention and data collection protocols to maintain consistency for all study participants. In experimental research, the control group receives the usual treatment or a placebo ( any treatment that has no active properties ) .

22. The three main types of controls are  positive, negative, and procedural, and variable controls . A positive control group is not exposed to the experimental treatment but is exposed to another treatment that is known to work. A negative control a process of conducting the experiment in the exact same way on a control group except that the independent variables are a placebo that is not expected to produce a result. procedural controls are designed to reduce error in conducting the experiement . variable control – the practice of keeping a variable constant to minimize its influence on results.

23. Manipulation Manipulation is the process of “doing something ,” a different dose of “something,” or comparing different types of treatment by manipulating the independent variable for at least some of the involved subjects. The independent variable might be a treatment, a teaching plan, or a medication . The effect of this manipulation is measured to determine the result of the experimental treatment on the dependent variable compared with those who did not receive the treatment.

24. Types of Experimental Designs There are many different experimental designs ( Campbell & Stanley, 1966). Each is based on the classic design called the true experiment or RCT. The classic RCT is conducted as follows: 1. The researcher recruits a sample from the population. 2. Baseline preintervention demographics, personal characteristics, and measurement of the intended study concepts or dependent variables are collected from the entire sample. 3. Subjects are then randomized to either the intervention or the control group. 4. After each group receives the experimental intervention or comparison/control intervention (usual care or standard treatment, education, or placebo), both groups complete postintervention measures to see if any changes have occurred in the dependent variables.

25. Pretest-post-test control group designs, Post-test only control group designs, Solomon four-group design, Factorial design , nested designs

26. subjects are randomly assigned to the 2 groups , both are presented, but only the experimental group is treated . After close observation, both groups are post-tested to measure the degree of change in each group.

27. Randomized control group post- test only design Usually planned where pretest is not necessary, unavailable, inconvenient, or likely to be reactive Controls internal validity factors E ( R ) C ( R ) X O 1 _ O 2

28. S ubjects are randomly selected and assigned to the 2 groups (control and experimental), and only the experimental group is treated . After close observation, both groups are post-tested, and a conclusion is drawn from the difference between these groups.

29. Randomized Solomon Four Group Design Pretested ( R ) O 1 X 1 O 2 Pretested ( R ) O 1 _ O 2 Un-pretested ( R ) _ X 1 O 2 Un-pretested R) _ _ O 2 Greater confidence can be placed on the findings

30. Cross-over design Also called as Rotation experiments / Cross-over design / Switch-over designs Here four experimental treatments are applied in a restrictively randomized manner in turn to four naturally assembled groups Groups X 1 X2 X3 X4 A t 1 t 2 t 3 t 4 B t 2 t 3 t 4 t 1 C t 3 t 4 t 1 t 2 D t 4 t 1 t 2 t 3

31. A crossover design is  a repeated measurements design  such that each experimental unit (patient) receives different treatments during the different time periods, i.e., the patients cross over from one treatment to another during the course of the trial.

32. Factorial design Factorial design involves  having more than one independent variable , or factor, in a study. Factorial designs allow researchers to look at how multiple factors affect a dependent variable, both independently and together. Factorial design studies are named for the number of levels of the factors.

33. R andomized block design A randomized block design is  an experimental design where the experimental units are in groups called blocks . The treatments are randomly allocated to the experimental units inside each block. When all treatments appear at least once in each block, we have a completely randomized block design.

34. Randomized Block Design(RBD ) Research design involves two principles Randomization Replication Control Data layout Let five treatments A, B, C, D and E replicated for 5 times respectively then the treatment allocation may be Block I Block II Block III Block IV Block V A E B E A B D C A D C A D C C D B E B E E C A D B