Table 1

Assignment rules and explanations of variables in the structural equation model

VariableAssignment rules or explanation
Caregiver’s educationIlliteracy, +1
Primary school, +2
Junior high school, +3
Senior high school and above, +4
Caregiver’s ageCaregiver’s integer age
Wealth IndexNumbers of accessories including phone (telephone or mobile), washing machine, refrigerator, TV set, access to internet
Parent-child interactionSix behaviours including read books to child, told stories, sang songs, took child outside the home, played with child, and named, counted or drew things to promote learning would form stimulus signals
Numbers of booksNumbers of books children owned presently
Score of ZSDSReversed score of caregiver’s depression assessed by ZSDS
Modified ICFIBreast feeding:
  • 6–9 months: No=0; Yes=+2;

  • 9–11 months: No=0; Yes=+2;

  • 12–35 months: No=0; Yes=+1.

Bottle feeding: Yes=0; No=+1;
Feeding frequency:
  • 6–9 months: 0 meal=0; one meal =+1; two meals or more =+2;

  • 9–11 months: 0 meal=0; 1–2 meals =+1; three meals or more =+2;

  • 12–35 months: 0–1 meals=0; 2–3 meals =+1; four meals or more =+2;

Dietary diversity: 0 group=0; 1–3 groups =+1; four or more groups =+2
Birth weightBirth weight of child (medical records or parental report)
Haemoglobin value for childrenHaemoglobin value we tested
CommunicationScore of communication assessed by ASQ
Gross motorScore of gross motor assessed by ASQ
Fine motorScore of fine motor assessed by ASQ
Problem-solvingScore of problem-solving assessed by ASQ
Personal-socialScore of personal-social assessed by ASQ
  • ASQ, Ages & Stages Questionnaires; ICFI, Infant and Child Feeding Index; ZSDS, Zung Self-rating Depression Scale.