What is the validity of a scale?

Validity refers to the extent to which a measure adequately represents the underlying construct that it is supposed to measure. Empirical assessment of validity examines how well a given measure relates to one or more external criterion, based on empirical observations. This type of validity is called criterion-related validity, which includes four sub-types: convergent, discriminant, concurrent, and predictive validity.

Is there any way to check the validity of a scale?

You are welcome Cleo!!

Thank you so much James!!

Sure. Despite no particular rules, the following are the points you should try to avoid:
• long complex questions
• double negatives
• double-barreled questions
• jargon or abbreviations
• culture-specific terms
• words with double meanings
• leading questions
• emotionally loaded words

Can you give any tips about how to design the items of questionnaire?

You are right. There are 3 major types of validity, namely content validity, criterion validity and construct validity.

Thx. I heard that there are different types of validity, right? How many of them and what are they?

It shows the extent to which it assesses what it is expected to assess.