Financial *v* non-financial incentive method |

Financial incentive (n=217) | 128 | 89 |

No financial incentive (n=217) | 103 | 114 |

χ^{2} analysis | χ^{2} = 5.78, 1 df, p=0.016 |

Individual administration methods (with/without financial incentive) |

Postal with financial incentive | 61 | 41 |

Postal without incentive | 55 | 47 |

χ^{2} analysis | χ^{2} = 0.83, 1 df, p=0.47 |

Telephone with financial incentive | 45 | 20 |

Telephone without incentive | 29 | 36 |

χ^{2} analysis | χ^{2} = 8.03, 1 df, p=0.005 |

Clinic visit with financial incentive | 22 | 28 |

Clinic visit without incentive | 19 | 31 |

χ^{2} analysis | χ^{2} = 0.37, 1 df, p=0.17 |