Table 1 Summary of all the variables in this study
Variable | Study instrument (Definition) | Type of variable |
|---|---|---|
Household | ||
 Region | Questionnaire | Categorical (Shanxi, Guizhou) |
 Single-child family | Questionnaire | Categorical (Yes, No) |
 Per capita net income | Questionnaire \( \left(\frac{\mathrm{Total}\ \mathrm{income}-\mathrm{Total}\ \mathrm{cost}\ \mathrm{of}\ \mathrm{production}}{\mathrm{Number}\ \mathrm{of}\ \mathrm{household}\ \mathrm{members}}\right) \) | Continuous (CNY) |
Caregiver | ||
 Age | Questionnaire | Continuous (Year) |
 Gender | Questionnaire | Categorical (Male, Female) |
 Role | Questionnaire | Categorical (Mother, Not mother) |
 Education | Questionnaire | Categorical (Illiterate, Primary school, Middle school, High school or above) |
 Depression | Zung Self-rating Depression Scale (Scores >50) | Categorical (Yes, No) |
Child | ||
 Age | Questionnaire | Continuous (Month) |
 Gender | Questionnaire | Categorical (Male, Female) |
 Stunting | WHO Child Growth Standards (Height-for-age Z-score < −2) | Categorical (Yes, No) |
 Wasting | WHO Child Growth Standards (Weight-for-height Z-score < −2) | Categorical (Yes, No) |
 Learning material | Questionnaire (Have picture books or toys) | Categorical (Yes, No) |
 Support for learning | Questionnaire (Engaged four or more activities) | Categorical (Yes, No) |
 Developmental delay | Age and Stages Questionnaire (Scores of one or more domains fall below the U.S. cut-off points) | Categorical (Yes, No) |