22. validity

what is validity

the extent to which an observed effect is genuine - does it measure what is was supposed to measure, and can it be generalised beyond the research setting within it was found?

validity in the spec

• face validity

• concurrent validity

• ecological validity

• temporal validity

what is internal validity

refers to whether the effects observed in an experiment are due to the manipulation of the IV and not another factor

a major threat is demand characteristics

what is external validity

relates more to factors outside of the investigation, such as generalising to other settings, populations of people and other eras

ecological validity

• the extent to which findings from a research study can be generalised to other settings and situations

if task is artificial, thus has low mundane realism, it has lower ecological validity

temporal validity

• the extent to which findings from a research study can be generalised to other historical times and eras

assessing validity

• face validity

• concurrent validity

face validity

• the measure is scrutinised to determine whether it appears to measure what it is supposed to measure

• can be determined by ‘eyeballing’ the measuring instrument or by passing it to an expert to check

concurrent validity

• extent to which a psychological measure relates to an existing similar measure

• close agreement between the two sets of data would indicate the new test has high concurrent validity - and this is indicated if the correlation between the two sets of scores exceeds +0.8

what can validity be improved in

• experiments

• questionnaires

• observations

• qualitative research

experiments

improved in many ways

• using a control group to help assess causation

• standardised procedures to minimise impact of participant reactivity and investigator effects on validity of the outcome

• use of single-blind or double-blind procedures

questionnaires

• many incorporate a lie scale within questions in order to assess the consistency of a respondent’s response and to control for the effects of social desirability bias

• validity may be further enhanced by assuring respondents all data submitted will remain anonymous

observations

• may produce findings high in ecological validity as there may be minimal intervention by the researcher - especially the case if the observer remains undetected, as in covert observations, meaning the behaviour of those observed is likely to be natural and authentic

• behavioural categories that are too broad, overlapping or ambiguous may have a negative impact on the validity of the data collected

qualitative research

• usually thought as having higher ecological validity as depth and detail associated with case studies and interviews is better able to reflect a participants reality

• researcher may still have to demonstrate the interpretive validity of their conclusions - the extent to which the researcher’s interpretation of events matches that of their participants

• can be demonstrated through things such as the coherence of the researchers narrative and the inclusion of direct quotes from participants within the report

• validity is further enhanced through triangulation - use of a number of different sources as evidence eg data compiled through interviews with friends and family, personal diaries, observations etc