Experimenal research designes

types of research design

1. EXPERIMEN Research DESIGN By Nimra farooq Roll no# f16-0714 Bs 5 - psychology Submitted to: Ma’am Andleeb

2. INTRODUCTION … Experimental is most scientifically sophisticated research method . It is defined as ‘observation under controlled conditions ’. Experimental research design are concerned with examination of the effect of independent variable on the dependent variable, where the independent variable is manipulated through treatment or intervention(s), & the effect of those interventions is observed on the dependant variable

3. TRUE EXPERIMENTAL DESIGN

4. CONCEPT… True experimental research designs are those where researchers have complete control over the extraneous variables & can predict confidently that the observed effect on the dependable variable is only due to the manipulation of the independent variable

5. ESSENTIAL CHARACTERISTICS… A true experimental research design must essentially consist of the following three characteristics:  Manipulation  Control  Randomization

6. MANIPULATION: Manipulation refers to conscious control of the independent variable by the researcher through treatment or intervention(s) to observe its effect on the dependent variable . In other words, it is a conscious act by the researcher, where he or she varies the independent variable & observes the effect that manipulation has on the dependant variable of interest.

7. COUNT… For example, a researcher is conducting a study on efficacy of cholrhexidine mouthwash on the prevention of ventilator-associated pneumonia (VAP) among patients admitted in ICUs.  In this example, chlorhexidine mouthwash is the dependent variable, which is manipulated by the researcher, & is used as an intervention for the experimental group, while the control group is kept deprived of it to observe its effect on the incidence of VAP

8. CONTROL: Control is another essential element of true experimental design.  Control refers to use of control group & controlling the effects of extraneous variables on the dependent variable in which researcher is interested.  The subject in the control & experimental groups are similar in number & characteristics, but the subject in the control group receive no experimental treatment or any intervention at all.

9. COUNT… The experimental group receives the planned treatment or intervention & a comparison is made with the control group to observe the effect of this treatment or intervention . Generally in health care & nursing research, it is not ethically feasible keep a control group deprived of interventions; however, existing conventional method of interventions may be compared with experimental interventions.

10. RANDOMIZATION: Randomization means that every subject has an equal chance of being assigned to experimental or of study subjects on a random basis . Through random assignment of subject under experimental or control group, chances of systemic bias is eliminated . Randomization is used in true experimental research design to minimize the threat of internal validity of the study & to eliminate the effect of extraneous variables on dependent variables . Through randomization, on average the characteristics of the subject in experimental & control groups are similar, thus influence of extraneous variables on dependant variable is eliminated by dispersing the variability of the subject characteristics equally in both the groups.

11. COUNT … METHODS OF RANDOMIZATION: Random assignment of subject may done with simple flip of a coin for each subject; if coin lands on its ‘head’, subjects are assigned to first group & with ‘tail’ subjects are assigned to control group . Another possible method is to write the names of the subjects on slips of paper & put the slips into a bowl & then draw lots. The first designated numbers of subjects are placed in one group, & rest are assigned under another group . Thirdly a random table may be used to facilitate the randomization process. In this method, blind-folded subjects choose a number from a table of number horizontally (row) or vertically (columns), till a requisite number is reached for both experimental & control groups. Computer-assisted random sequences also may be used for the random assignment of the subjects

12. TYPES OF THRUE EXPERIEMNTAL DESIGN True Experiential Design Post-test only Pretest post-test only Randomized block Solomon 4 groups Factorial Crossover

13. POST-TEST-ONLY CONTROL DESIGN: Composed of two randomly assigned group, i.e. experimental & control, but neither of which is pretested before the implementation of treatment on the experimental group . In addition, while treatment is implement on the experimental group only, post-test observation is carried out on both the group to assess the effect of manipulation . This design can be helpful in situations where it is not possible to pretest the subjects . For example, to study the effect of an educational intervention related to urinary incontinence on the subsequent help-seeking behavior of older adults.

14. COUNT… Random assignment Control group Treatment Post-test Post-test Exp. group

15. RETEST-POST-TEST-ONLY DESIGN In this research designs, subjects are randomly assigned to either the experimental pr the control group . The effect of the dependent variable on both the groups is seen before the treatment (pretest ). Later, the treatment is carried out on experimental group only, & after-treatment observation of dependant variable is made on both the groups to examine the effect of the manipulation of independent variable on dependant variable . For example, such a design could be used for ‘an experimental study to assess the effectiveness of cognitive behavioral therapy interventions for patients with breast cancer.

16. COUNT… Random assignment Control group Treatment Post-test Post-test Exp. group Pre- test Pre- test

17. SOLOMON FOUR-GROUP DESIGN There are two experimental groups (experimental group 1 & experimental group 2) & two control groups (control group 1 & control group 2 ). Initially, the investigator randomly assigns subjects to the four groups . Out of the four groups, only experimental group 1 & control group1 receives the pretest, followed by the treatment to the experimental group 1 & experimental group 2 . Finally , all the four groups receive post-test, where the effects of the dependant variables of the study are observed & comparison is made of the four groups to assess the effect of independent variable (experimental treatment) on the dependant variable

18. COUNT… in this, experimental group 2 was observed at one occasion, & that score should be similar to average scores of those in experimental & control groups . To estimate the amount of change in experimental & control group 2, the average test scores of experimental & control groups 1 are used as baseline The Solomon four-group design is believed to be most prestigious experimental research design, because it minimizes the threat to internal & external validity.

19. COUNT… Random assignment Control Group 1 Exp. Group 1 Exp. Group 1 Control Group 1 pretest Pretest Treatment Treatment Post-test Post-test Post-test Post-test

20. COUNT… Example. Third graders are randomly assigned to 1 of 4 groups. The “knowledge of language” is measured in groups 1 and 2. Groups 1 and 3 are given a special study on the language learning. When the special study is over, all four groups are tested.

21. COUNT… - the first and the second groups are retested; - the first and the third groups are exposed to the treatment, and the second and the fourth groups are taken as control groups; - all four groups are posttested . This design provides the best result but it requires a large sample so that enough subjects could be assigned to four groups. When the sample is large, administering the tests becomes difficult, time and energy consuming.

22. FACTORIAL DESIGN In factorial design, researcher manipulates two or more independent variables simultaneously to observe their effects on the dependant variables . This design is useful when there are more than two independent variables, called factors to be tested . For example , a researcher wants to observe the effect of two different protocols of mouth care on prevention of VAP when performed at different frequencies in a day . This design also facilitates the testing of several hypothesis at a single time . Typical factorial design incorporates 2X2 or 2X3 factorial, but it can be in any combination . The first number (α) refers to the independent variables or the type of experimental treatments, & the second number (β) refers to the level or frequency of the treatment.

23. FACTORIAL DESIGN

24. QUASI – EXPERIMENTAL RESEARCH DESIGN

25. Quasi-experimental Designs The term quasi- (pronounced kwahz-eye) means almost, near, partial, pseudo , or somewhat. Quasi-experimental designs are used when true experiments cannot be done. A common problem in educational research is the unwillingness of educational administrators to allow the random selection of students out of classes for experimental samples. Without randomization , there are no true experiments. So, several designs have been developed for these situations that are “ almost true experiments ,” or quasi-experimental designs . We’ll look at three: the time series the nonequivalent control group design , the counterbalanced design.

26. Continue.. Quasi-experimental research design involves the manipulation of independent variable to observe to effect on dependant variable, but it lacks at least one of the two characteristics of the true experimental design; randomization or a control group.  In other words, quasi-experimental designs have an element of manipulation but lack at least one of the other two properties that characterize true experiments; randomization or a control group.  Quasi-experimental designs are generally used to establish the causality (effect of independent variable on dependent variable) in situations where researchers are not able to randomly assign the subjects to groups or for various reasons no control group is available for an experimental study.

27. MAIN CHARACTERISTICS Manipulation of the independent variables to observe the effects on the dependant variables . Lack of at least one of the two other essential characteristics of the true experiment, i.e. random assignment of subject or a control group . Quasi-independent variables are used instead of true independent variables. Where independent variable is not manipulates in complete controller situations.

28. TYPES OF QUASI-EXPERIMENTAL DESIGN Nonrandomized control group design Time-series design

29. NONRANDOMIZED CONTROL GROUP DESIGN It is also known as the ‘nonequivalent control group design ’. This design is identical to the pretest-posttest control group design, except there is no random assignment of subjects in experimental & control groups . In this design, experimental & control groups are selected without randomization, & dependent variables are observed in experimental as well as control groups before the intervention . Later, the experimental group receives treatment & after that posttest observation of dependant variables is carried out for both the groups to assess the effect of treatment on experiment group

30. COUNT… For example , this method was used to study ‘the effects of integrated self esteem on quality of work of participents: a quasi experiment’. A nonequivalent pretest-posttest control group design was used in this study . Data was collected by through a questionnaire . Regarding the effects of the intervention on the quality of work factors, the result included an increase of social support by supervision. The intervention on the psychosomatic wards was unsuccessful, through the introduction of integrated care on the somatic wards was fairly successful.

31. High Self-Esteem Group Low Self-Esteem Group 17 12 19 10 16 14 12 15 17 13 18 12 15 11 16 13 Any Difference Variable 1: Self-Esteem not manipulated but used to define two groups of participants Variable 2: Academic Performance (the Dependent Variable) Measured in each of the two groups Participant Variable Self-Esteem Variable Academic Performance A 84 16 B 72 10 C 90 19 D 68 13 E 77 16 F 81 12 G 85 17 H 78 13

32. TIME-SERIES DESIGN This design is useful when the experimenter wants to measure the effects of a treatment over a long period of time . The experimenter would continue to administer the treatment & measure the effects a number of times during the course of the experiment . Generally it is a single-subject research, in which the researcher carries out an experiment on an individual or on a small number of individuals, by alternating between administering & then withdrawing the treatment to determine the effectiveness of the intervention. Exp . group 01 02 03 Treatment 01 02 03

33. COUNT… A researcher might assess pain levels of a group of patients with low-back pain. After 3 weeks of pain assessment, subjects are taught special exercises to reduce that pain. During the next 3 weeks, pain levels would again be measured . Measuring a child’s school performance on a weekly basis, & then introducing a new teaching technique. Then again measuring on a weekly basis

34. O1 O2 O3 O4 O5 O6 Observations Before Treatment Observations After Treatment Treatment Average score A Time Series Study with Multiple Observations Before and After Treatment

35. ADVANTAGES OF QUASI-EXPERIMENTAL DESIGN Quasi-experimental designs are more frequently used because they are more practical & feasible to conduct research studies in nursing, where in the absence of a large sample size, randomization &/ or availability of control groups are not always possible . This design is more suitable for real-world natural setting than true experimental research designs . It allows researchers to evaluate the impact of quasi independent variables under naturally occurring conditions . It may be able to establishing casual relationship. Wherein some of the hypotheses are practically answered through this design only

36. DISADVANTAGES OF QUASI-EXPERIMENTAL DESIGN There is no control over extraneous variables influencing the dependant variables . The absence of a control group or lack of control over the research setting makes the results of this design less reliable & weak for the establishment of casual relationship between independent & dependant variables.

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