Dyslexia Quest is a low cost, quick screener that looks broadly for typical signs of dyslexia.
A screener is not designed to generate a definitive identification of dyslexia, it is meant to provide a fast and low cost snapshot of difficulties.
The screening provides further information so you can consider whether it would be advisable to either invest in specialist teaching or further investigation with a more specific assessment.
The typical difficulties the screener looks for are often shown by children within the age categories but it will not be as accurate as an assessment designed for specific ages. Dyslexia Quest would be considerably more accurate with a granular age range but to do this requires many years of research and testing which will increase the program cost significantly. A screener is not meant to replace an assessment by an educational psychologist (or qualified specialist teacher), such an assessment will take 2-3 hours and typically cost between £700-£2000. There is often a delay of many months before a specialist assessment can be secured so there are significant advantages to taking a quick screener before an assessment.