Validation of an instrument means that individuals and organizations can make reliable strategic decisions, based on survey results, about where to focus their development efforts.
In order for an instrument to be valid it needs to be compared to another measure. In most cases the other measure is internal performance within the organization such as rate of promotion, bonus as related to salary, etc. If there is consistent high correlation between an assessment measure and the performance measures internally then the instrument is valid.
Leaders, managers and individual contributors can trust that our assessments are valid measures of the skills required for high performance on the job.