reliability and validity

reliability

reliabilty is the consistencey of the results are the same.
test re-test: is when you test the same participants some time after the original study: usually a week or so: for the results to be reliable the participants should get the same score that they did before.
split half: compares a participants performance on two halves of a test or questionnaire- there should be a close correlation between scores on both halves of the test. questions in both halves should be of equal quality for good internal reliabilty.
inter- rater reliability: refers to the consistency of a researchers behaviou. a researcher should produce similar test results etc in the same way as another researcher. consistency improves reliability.
increase reliability by standardising instructions and carry out a pilot study to improve the procedures and the materials.

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internal validity= the tool is measuring what it intended to
external validity= the findings can be generalized beyond the context of the research situation.
face validity= does the measuring tool appear to be doing what it should? one or more judges assess whether the test seems appropriate and suggest changes if necessary.
concurrent validity= established by comparing performance on a new questionnaire with a previously established test on the same topic.
predicitive validity= can an intelligance test at age 3 predict academic performance at 21?
temporal (historical) validity= do our findings endure over time or they era- dependent?
context validity, better known as:
ecological validity= can we apply our findings to other contexts and situations outside of the research setting?
population validity= can we generalise findings from our research particpants to other population groups?

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