Table 1. Summary of the main types of reliability and validity applied to welfare assessment.

Reliability or Validity	Type of reliability or validity	Brief description
Reliability	Intra-rater reliability	Assess consistency when one person repeat-scores the animal within a short time period such as 2 to 7 days or ideally at the same time point
	Inter-rater reliability	Assess consistency when scorers simultaneously score the same animal within a short time period such as 2 to 7 days or ideally at the same time point.
	Test-re-test reliability	Assess consistency in scoring over a longer period (e.g. more than 2 weeks)
	Internal consistency	Assess the level of associations between grouped questions or measures
Validity	Content validity (e.g. face validity)	Assess whether individual questions really ask what they are meant to be asking
	Concurrent criterion validity	Compare measure to an independent “gold standard” measure
	Predictive or known groups criterion validity	Assess measures ability to predict a future outcome or distinguish between groups