What are average scaled scores on the Bayley Scales?

The Bayley Scales of Infant and Toddler Development doesn't use a simple "average scaled score." Instead, it reports scores in several ways, and the average depends on which score you're looking at:

* Scaled Scores: These have a mean of 10 and a standard deviation of 3. So, a scaled score of 10 is considered average for a given subtest. A score of 7-9 is considered below average, while 11-13 is above average. Scores outside of this range are significantly below or above average.

* Composite Scores: The Bayley also provides composite scores (e.g., Cognitive, Language, Motor). These composite scores also have a mean of 100 and a standard deviation of 15. Therefore, a composite score of 100 is considered average overall.

It's crucial to understand that *a scaled score of 10 on one subtest doesn't equate to a composite score of 100*. The composite scores are derived from several subtests. Interpreting the results always requires understanding the individual scaled scores and the composite scores, along with consideration of the child's developmental history and context. A qualified professional should always interpret Bayley scores.