*2.7. Statistical Analyses*

#### 2.7.1. IYCD Item-by-Item Analyses

An exploratory item-by-item analysis was conducted using logistic regression with the log odds of the probability of passing regressed on the natural logarithm of age to determine how well each item performed across countries. The age at which 50% of children passed an item and the slope of the curve were extracted for each country, and both empiricaland model-based probabilities of passing an item were plotted against age to provide a graphical representation of item trajectories for each country.
