Validity (as used here) refers to whether the data actually represent what you think is being measured.
Data is valid if it accurately represents what you believe is being measured.
The data is only valid if you think it is being measured correctly, not if it actually represents what you think is being measured.
Two men are sitting down on the ground.
After 20 years of representation the Bureau won a victory.
The tanks are only for saltwater fish.
A girl is writing in her diary.
A man is sleeping.
The children sleeping.