Paper Topic:

internal vs. external validity

Running Head : INTERNAL VS . EXTERNAL VALIDITY

Comparison and Contrast

Of Internal Validity with

External Validity

[Name of Author]

[Affiliation of author]

Comparison of Internal Validity with External Validity

Understanding first what is Internal Validity and External Validity in Educational Psychology would help us determine their similarities and differences . We should then cite examples where Internal Validity or External Validity is more appropriate to use than the other

Internal Validity , according to Huitt et . Al (Jan 1999 , refers to firstly , how well a study had gone (research design , operational

br definitions used , how variables were measured , what was /wasn 't measured etc ) and then secondly , how confidently one can conclude that the change in the dependent variable was produced solely by the independent variable and not irrelevant ones . Furthermore , Huitt added , that in descriptive studies , internal validity refers only to the accuracy /quality of the study

In Campbell and Stanley 's classic book on experimental research , eight types of irrelevant variables had been cited that affects greatly to an experiment 's internal validity

On the contrary , External Validity , according again to Huitt , is the extent to which a study results irrelevant variables . Randomization is the usual cause of higher external validity . A group research employing randomization will initially possess higher external validity than with studies that do not use random selection /assignment

In support for External Validity , Huitt had affirmed Campbell and Stanley idea that four factors adversely affect study 's external validity

Internal Validity 's Irrelevant Variables

History . Studies that conduct experiments with repeated measures over a long period of time would be more affected by this variable than experiments that gather data over a short period of time

Maturation . This is also related to time but this does focus on subjects that were part of the study such as if a resource person would be needed through a certain long period of time , then he would be subject to become tired or bored , more or less motivated because of thirst or hunger

Testing . This does affect the result of the study since the resource had already experience a similar experiment and he could then change his answer on the second time around

Instrumentation . The change of used measurements could also change the results gathered for a study . The use of persons as reference could also lead to a change in instrumentation through time

Statistical Regression

Selection

Experimental Mortality

Selection Interactions

External Validity 's four factors

Interaction

Pretesting

Setting

Multiple Treatments /Intervention

References

W . Huitt , J . Hummel , D . Kaeck (Jan . 1999 . Retrieved March 18 , 2008 from

http /chiron .valdosta .edu /whuitt /col /intro /valdgn .html

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