how many types of validity?

There are several types of validity, but the main categories include content validity, construct validity, and criterion-related validity. Content validity assesses whether a test measures the intended content area, construct validity evaluates whether a test truly measures the theoretical construct it claims to measure, and criterion-related validity examines how well one measure predicts an outcome based on another measure. Each type plays a crucial role in ensuring the reliability and accuracy of research and assessments.