reliability and validity

what is internal reliability

this concerns the extent to which something is consistent within itself, for example, a set of scales should measure the same weight between 50 and 100g as between 150 and 200g

what is external reliability

this concerns the extent to which a test measures consistantly over time

how is the split half method used and what type of reliability does it improve

it measures internal reliability by splitting a test into 2 halves and having the same ppt do both halves. if the 2 halves of the test provide similar results this indicates that the test has high internal reliability

how is the test-retest method used and what type of reliability does it improve

this measures external reliability by giving the same test to the same ppt on 2 occasions. if the same result is obtained then the test has external reliability

what is inter-observer reliability and how to improve it

this measures whether different observers are viewing or rating behaviour in the same way. if it is low this could lead to ot indicate a biased observation.

inter-observer reliability can be improved by:

• developing clearly defined and seperate categories for observational criteria

• increase the number of observers as data will be less subject to bias

• record the test so it can be reviewed at any time.

what is the accepted reliability correlation coefficient in psychology

0.8/ 80%

what is validity in general

validity concerns the accuracy- the degree to which something measures what it claims to measure and the extent to which findings can be generalised beyond research settings

what is internal validity

this concerns whether results are to do with the manipulation of the IV and not affected by confounding variables

what is external validity

this concerns the extent to which an experiments results can be generalised to other settings (ecological), other people (population) and over time (temporal).

what is face validity

it involves the extent to which items look like what a test claims to measure

what is concurrent validity

assesses validity by correlating scores on a test with another test that is already known to be valid

e.g IQ

what is predictive validity

this involves testing a group of subjects and then comparing scores to results obtained at some point in the future to see if they match

what is temporal validity

use the test re-test method in another time context and see if the same results are found