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Experimental Research - Coggle Diagram
Experimental Research
Quasi- Experimental Designs: Identical to true experimental design but does not have random assignment and results in groups that are non-equivalent. These designs are inferior to true experimental designs internal validity due to variety of selection related threats such as history or maturation threats
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Factorial Designs: Allows for manipulation of two or more independent variables. Each independent variable is called a factor and each sub-division of a factor is called a level. Allows the researcher to examine the individual effect of treatment on each dependent variable (main effect) and the joint effect (interaction effect). Most basic design is 2 x 2- each number represents a factor and the value of each factor represents the number of levels in the factor
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One or more independent variables are manipulated by the researcher (as treatments), subjects are randomly assigned to different treatment levels and the results of the treatments (dependent variable) are observed. Strength is the internal validity to link cause and effect through treatment manipulation.
Basic Concepts
Treatment and control group: subjects are administered one or more experimental stimulus called treatment (treatment group) and the other subjects and not given anything (control group)
Treatment manipulation helps control the "cause" in the cause-effect relationship .Must be checked using pretest and pilot tests prior to the study.
Random selection and assignment: Random selection process of randomly selecting a sample from population. Random assignment is randomly assigning subjects to experimental or control groups
Threats to internal validity include history threats, maturation threat, testing threat, regression threat, mortality threat and instrumentation threat