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Experimental research design definition

experimental research design advantages and disadvantages and characteristics of experimental research design
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JaydenGibbs,United States,Teacher
Published Date:19-07-2017
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Zainal A. Hasibuan, PhD  (  STUDY PROGRAM: MAGISTER INFORMATION TECHNOLOGY, COMPUTER SCIENCE FACULTY, UNIVERSITY OF INDONESIA Research Methods   (upon which methodologies can be built)  Case Study Types of Research Methods Experimental Research Experimental Group Designs  Three Types  Experimental Quasi-experimental Non-experimental l_____________l_____________l What is Experimental Design?  •  An experimental design:   “Is the tradi?onal approach to conduc?ng  quan?ta?ve research”  Sumber: Creswell, J.C. 2005 Experimental Design  •  Treatment, control, comparison  •  do something to subjects (guinea pigs?)   •  who are randomly selected and randomly assigned to  groups  •  for the purpose of determining the cause of an effect  (difference between groups) CharacterisDcs of Experiments  •  Random assignment  •  Control over extraneous variables  •  Manipula?on of the treatment condi?ons  •  Outcome measures  •  Group comparisons  •  Threats to Validity Random Assignment  •  Random assignment is the process of assigning individuals to  the treatments.  •  The random assignment of individuals to groups (or condi?on  within a group) dis?nguishes a rigorous’ “true” experiment  from an adequate, but less‐than‐rigorous, “quasi‐experiment”. Experimental Research  •  Experiment: The inves?ga?on of the  rela?onship between two or more variables by  deliberately producing a change in one  variable in a situa?on and observing the  effects of that change on other aspect of the  situa?on.  •  Cause‐and‐effect Experimental Research  •  Experimental manipula?on: Change that an  experimenter deliberately produces in a  situa?on  •  Treatment: the manipula?on implemented by  experimenter  •  Experimental group: any group receiving a  treatment in an experiment Experimental Research  •  In an observa(onal study , measurements of variables  of interest are observed and recorded, without  controlling any factor that might influence their  values.  •  An experiment, on the other hand, deliberately  imposes some treatment on individuals in order to  observe their responses.  •  In principle, only experiments can give good evidence  for causa?on. Steps In ConducDng Experimental Research  •  Step 1. Decide if an experiment addresses your research problem  •  Step 2. Form hypotheses to test Cause‐and‐effect Rela?onships  •  Step 3. select an Experimental Unit and Iden?fy Study par?cipants  •  Step 4. Select an Experimental Treatment and Introduce it  •  Step 5. Choose a Type of Experimental design  •  Step 6. Conduct the Experimental  •  Step 7. Organize and Analyze the Data  •  Step 8. Develop an experimental Research Report  Sumber: Creswell, J.C. 2005 The Road to Experimental Research Types of Experimental Designs  •  Between‐Group Designs  – True experiments (pre‐and posaest, posaest only)  – Quasi‐experiments (pre‐and posaest, posaest only)  – Factorial Design  •  Within‐Group or Individual Designs  – Time series experiments (interrupted, equivalent)  – Repeated measures experiments  – Single‐subject experiments Types of Experimental Design  True Quasi Factorial Time Series Repeated Single Subject Experiment Experiment Measures Random assignment? Yes No May be Used No No No Number of groups/ Two or more Two or more Two or more One group One group One individual individuals compared? studied at a time Number of One or more One or more Two or more One or more Two or more One or more interventions used? interventions interventions interventions interventions interventions interventions Number of times the Once Once Once After each After each Multiple points dependent variables intervention intervention measured/observed? Controls typically Pretest Pretest Pretest Group Covariates Individuals used? matching, matching, matching, becomes its become their blocking, blocking, blocking, own control own controls covariates covariates covariates Types of Between‐Group Designs  (True Experimental Designs)  Pre-and Posttest Design Time Random Control Pretest No Treatment Posttest assignment Group Random Experimental Pretest Experimental Posttest assignment Group Treatment Posttest-Only Design Time Random Control Group No Treatment Posttest assignment Random Experimental Experimental Posttest assignment Group Treatment Types of Between‐Group Designs  (Quasi Experimental Designs)  Pre-and Posttest Design Time Select Control Pretest No Treatment Posttest Group Select Experimental Pretest Experimental Posttest Group Treatment Posttest-Only Design Time Select Control Group No Treatment Posttest Select Experimental Experimental Treatment Posttest Group Experiment Example  •  New “instant breakfast” product.  •  To assess its nutri?onal quality, researchers in the lab  feed 30 newly weaned male white rats and measure  their weight gains over a 28‐day period.  •  They randomly select 15 rats and feed them using  the new product.  •  The other 15 rats receive a standard diet. Design of Experiments  •  Experimental units: individuals on which the experiment is  done, also called subjects when the units are human beings.  –  The rats  •  Treatment: the specific experimental condi?on applied to the  units.  –  “instant breakfast” diet  •  Factors: the explanatory variables, which ogen have levels.  –  the diet Principles of Experimental Design  •  Control  – Researcher decides which subjects areassigned to the  treatment group  •  Randomiza?on  – Impar?al and objec?ve  •  Replica?on  – Reduces chance varia?on in the results and can help  achieve sta?s?cal significance