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Unformatted text preview: 1. Internal validity . ¬∑ The definition of internal validity is the degree to which one can infer that a causal relationship exists between two variables. 2. External validity . ¬∑ The definition of external validity is the extent to which the study results can be generalized to and across populations of persons, settings, times, outcomes, and treatment variations. Internal validity, as described earlier, refers to the degree to your independent variable actually created any change that you can observe in your dependent variable (Bracht & Glass, 1968.) External validity, as described earlier, refers to the extent to which the results of a research study can be generalized confidently to a group larger than the group that participated in the study (Bracht & Glass, 1968.) Factors which jeopardize internal validity History is a threat to internal validity and it refers to events that occur between the DV measurements in a repeated-measures design (Smith & Davis, 2010). Outside events may manipulate subjects in the direction of the research experiment or between constant measures of the dependent variable. Assume that the dependent variable is calculated twice for a set of subjects, one time at Time A and soon after at Time B, and that the independent variable is set up in the interim. Presume also that Event A transpires amid Time A and Time B. If results on the dependent calculation vary at these two times, the inconsistency may be owing to the independent variable or to Event A. One example would be an experiment of the efficiency of a new technique for teaching a section on the biology of a cell, understanding that we comprehend that several of the schoolchildren had just watched a television documentary that was named ‚ÄúThe Cell.‚ÄĚ This would be an example of previous history influencing the results of a study. Maturation is a threat to internal validity; refers to changes in participants that occur over time during an experiment; could include actual physical maturation or tiredness, boredom, hunger, and so on (Smith & Davis, 2010). The subject matter may alter in the direction of the experiment or amid repetitive measures of the dependent variable due to the course of time per se. A few of these modifications are long-lasting like for example biological growth and other adjustments are short-term like for example fatigue. Reason that the dependent variable is estimated twice for a subject group, on one occasion at Time A and afterward at Time B, and that the independent variable is established in the interim. If marks on the dependent assessment fluctuate at these two times, the incongruity may be appropriate to the independent variable or to naturally happening developmental methods. One example would be that of children growing up. Children are mainly prone to maturation because they are biologically altering so quickly. In summary, if you have a maturation effect in use, it is confounded with the treatment offered in the research experiment and you do not know whether the alteration observed from pretest to posttest is because of the treatment or simply owed to maturation.from pretest to posttest is because of the treatment or simply owed to maturation....
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This note was uploaded on 01/08/2012 for the course PSY326 326 taught by Professor Angelawillis during the Spring '11 term at Ashford University.
- Spring '11