Model and age group | Primary sample | Cross-validation sample | ||

Adjusted R^{2} | see mL·min^{−1} | Adjusted R^{2} | see mL·min^{−1} | |

Linear model | ||||

All | 0.55 | 572.89 | 0.54 | 487.84 |

≤20 years | 0.71 | 560.65 | 0.81 | 528.86 |

>20 years | 0.50 | 574.43 | 0.37 | 484.56 |

Polynomial model | ||||

All | 0.56 | 566.20 | 0.57 | 476.72 |

≤20 years | 0.71 | 548.80 | 0.82 | 456.03 |

>20 years | 0.51 | 568.37 | 0.38 | 478.26 |

Additive model | ||||

All | 0.57 | 556.50 | 0.57 | 473.15 |

≤20 years | 0.76 | 495.18 | 0.84 | 420.72 |

>20 years | 0.52 | 563.82 | 0.38 | 476.92 |

see: standard error of the estimate.