Personality tests and flawed measurements

People can vary in degrees from low to high on a given trait. Currently, the most scientifically supported theory is the Big 5, which identifies the degree to which someone is open to new experiences, conscientious, extraverted, agreeable, and emotionally stable.

But even most Big 5 tests still use a traditional Likert-type scale, which asks participants to rate themselves “on a scale of 1 to 5.” Scientists have been aware for decades that this measurement method is fraught with biases.