Validity (DP IB Psychology): Revision Note

Validity is the extent to which the findings of a study are true to life and measure what they are intended to measure

• Do the findings reflect how people really think, feel, and behave?

• Do they measure what the researcher set out to investigate?

• Could extraneous factors have influenced the results?

• Can the findings be generalised to wider populations, contexts, and times?

Internal validity measures the extent to which the results are due to the manipulation of the IV rather than the influence of extraneous or confounding variables

This ensures the study demonstrates a clear cause-and-effect relationship

• Bandura's (1961) investigation into social learning theory used the same toys and the same actions by the aggressive model

• Asch's (1951) research on conformity used the same line-length stimuli, with the participant seated at the same place at the table, on each of the critical and non-critical trials

High internal validity means that the conclusions drawn from a study are trustworthy and free from outside factors

External validity measures the extent to which the results can be generalised beyond the research setting

Ecological validity is a type of external validity that refers to how realistic the task/environment is

External validity is high when the task participants are given is more aligned to a real, everyday experience rather than a task that is artificial or contrived or when their engagement with the task is real, even if the task itself is artificial (lacks mundane realism)

• Dickerson (1992) used naive participants in a real setting to investigate the effect of commitment on prosocial behaviour

• Boyden (2003) documented the lived experiences of children living in war zones

High external validity means the results are transferable to different populations and settings and scenarios

Temporal validity measures the extent to which research findings are relevant over time

• E.g., Asch's research reflect the post-WWII social climate; it's unlikely to show the same conformity levels today

• Bowlby’s maternal-deprivation theory is outdated due to changing family structures

  • E.g., single parents, blended families, stay-at-home fathers, same-sex parents

High temporal validity means that a study's findings apply across different time periods (past, present, future)

Construct validity refers to how well a study measures the psychological construct (theory/idea) it claims to investigate

It is important for abstract concepts (e.g., intelligence, mood, depression)

Researchers must show their measurement aligns with theoretical understanding.

• E.g., Asch used a task which was unambiguous so if the participants conformed it was clear evidence of conformity

High construct validity means that a study's findings accurately represents the theory in action

Predictive validity measures how well a study's findings predict a future outcome or behaviour

• E.g., Ainsworth's (1970) Strange Situation research categorises people into different attachment styles as infants which predict future relationship behaviours

High predictive validity means that a study's findings forecast future behaviour which could be used in educational or business settings for example