Child development with the D-score: turning milestones into measurement [version 1; peer review: 1 approved with reservations]

The chapter equips the reader with a basic understanding of robust psychometric methods that are needed to turn developmental milestones into measurements, introducing the fundamental issues in defining a unit for child development and demonstrates the relevant quantitative methodology.
It reviews quantitative approaches to measuring child development;
introduces the Rasch model in a non-technical way;
shows how to estimate model parameters from real data;
puts forth a set of principles for model evaluation and assessment of scale quality;
analyses the relation between early D-scores and later intelligence;
and compares the D-scores from three studies that all use the same instrument.