PPVT-R Raw Score at Given Age | Equation From Growth Model | Estimated Score |
---|---|---|

3 y | 12.2 + 17.4 (3 − 3) − 0.7 (3 − 3)^{2} | 12.2 |

4 y | 12.2 + 17.4 (4 − 3) − 0.7 (4 − 3)^{2} | 28.9^{a} |

11 y | 12.2 + 17.4 (11 − 3) − 0.7 (11 − 3)^{2} | 106.6 |

12 y | 12.2 + 17.4 (12 − 3) − 0.7 (12 − 3)^{2} | 112.1^{b} |

On the basis of the computed estimates from the growth-curve model, the following equation could be derived: 12.2 + 17.4 (age − 3) − 0.7 (age − 3)

^{2}. Age is centered around 3 years (the age at the beginning of the study period), to facilitate interpretability of the parameter estimates.↵a PPVT-R raw score increase from 3 to 4 years = 16.7 points.

↵b PPVT-R raw score increase from 11 to 12 years = 5.5 points.