Final answer:
The validity coefficient determines the accuracy and reliability of measurements and is affected by irregularities in the object being measured.
Step-by-step explanation:
The validity coefficient measures the extent to which a given instrument or tool accurately measures what it's supposed to measure. It determines the accuracy and reliability of the measurements obtained from the instrument or tool. When the validity coefficient varies greatly, it suggests that there may be irregularities in the object being measured or other factors that affect the outcome.