Validity & Reliability

Question 1

Define reliability

Answer 1

Used in statistics to imply the consistency of a measure

Question 2

Define validity

Answer 2

Determined by whether a test accurately measures what it is supposed to measure

Question 3

Are reliability & validity indepdendent of each other?

Answer 3

Yes

I.e. a measurement can be valid but not reliable, or reliable but not valid

E.g. if a pulse oximeter records the O2 sats 5% below the true value every time it is used then from a statistical point of view it is ‘reliable’ but not ‘valid’ (as the reported saturations are not an accurate reflection of the true values).