8. Z-Score
Weight for age
Assume we have 19 month old boy and weights 9.8 Kg.
Reference standards for weight for age: 11.7 Kg for 19
Months old boy
9.8 Kg – 11.7 Kg = -1.9
Divide the results by the SD for the child’s age and gender
-1.9/1.2 sd = -1.58 SD units
-1.58 is the Z-Score for that child
Usual cut-off -2 Z-score