Validity
What is Validity?
Validity is the most important quality of any psychological test. It answers the simple question: “Does this test actually work?”
For an IQ test to be valid, it must demonstrate that the score it produces corresponds to real-world intelligence. It’s not enough to just generate a number; that number must predict something meaningful, like academic success, job performance, or problem-solving ability.
Types of Validity
- Construct Validity: Does the test actually measure the theoretical construct of “intelligence”? High correlation with other established tests (like validity between the Stanford-Binet and WAIS) is evidence of this.
- Predictive Validity: Does the score predict future outcomes? Professional IQ tests have high predictive validity for grades, income, and job complexity.
- Content Validity: Does the test cover a representative sample of cognitive skills (verbal, math, spatial), or is it too narrow?
Online Tests vs. Professional Tests
This is the main difference between a “real” IQ test and an internet quiz.
- Professional Tests (WAIS): Have spent decades gathering data to prove they actually measure cognitive ability (High Validity).
- Online Quizzes: Might output a number, but that number usually has no correlation to actual intelligence (Low/Zero Validity). They measure how good you are at that specific quiz, not how smart you are.