Validity: assessing and improving

What is validity?

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

What is internal validity?

The extent to which a study measures what it intends to within the research situation.

What two types of validity are forms of internal validity?

face validity and concurrent validity

What is external validity?

The extent to which results can be generalised beyond the study.

What three types of validity are forms of external validity?

ecological validity, population validity and temporal validity

What is ecological validity?

How well findings generalise toother settings

What is temporal validity?

Whether findings remain true over time and across cultures.

What is population validity?

the extent to which findings from a research of a sample can be generalised to the target population

What are the two ways of assessing validity?

by checking face validity or concurrent validity

What is face validity?

a basic form of validity where a measure is scrutinised to determine whether it appears to measure what it is supposed to measure

What is concurrent validity?

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

How can you improve validity in experimental research?

• using a control group gives the experimenter something to compare the changes in the DV to the effects of the IV

• use standardised procedures to minimise the effects of participant variables and investigator effects (extraneous)

• using a sing blind and double blind procedure also reduces extraneous variables, specifically demand characteristics

How can you improve validity in questionnaires?

• use a lie scale within the questions to assess the consistency of the ppts responses. This also reduces the effects of social desirability

• validity will be further enhanced by ensuring that all ppts are anonymous to encourage the truth

How can you improve validity in observations?

• observations with minimal input from the observer increases validity (non-ppt+covert) , reducing observer bias meaning the ppts behaviour is more likely to be natural and authentic

• ensure that behavioural categories are not too broad, not overlapping or ambiguous

How can you improve validity in qualitative research?

• already seen ad more valid than quantitative research due to depth and detail associated with case studies and interviews reflecting ppt’s reality

• researchers may also have to demonstrate interpretive validity - the extent to which the interpretation of events matches those of their ppts

• validity is further enhanced by triangulation - the use of a number of different sources as evidence e.g data compiled through interviews with family, friends, personal diaries, observations etc.