Statistical significance | Clinical significance | |

Yes | No | |

Yes | Diet A: | Diet B: |

n = 1,000 | n = 2,000 | |

Mean difference −7.0 kg | Mean difference −0.5 kg | |

95% CI −7.6 to −6.4 kg | 95% CI −0.9 to −0.1 kg | |

p-value <0.0001 | p-value = 0.025 | |

Conclusions: | Conclusions: | |

Large study | Large study | |

Large effect | Small effect | |

No | Diet C: | Diet D: |

n = 36 | n = 400 | |

Mean difference −3.0 kg | Mean difference −0.2 kg | |

95% CI −6.3 to +0.3 kg | 95% CI −1.2 to +0.8 kg | |

p-value = 0.07 | p-value = 0.69 | |

Conclusions: | Conclusions: | |

Study not large enough | Study probably large enough | |

Probably a real and moderate effect, but insufficient results to draw a reliable conclusion | Probably a small effect |

Effect size is the mean difference in weight (new diet minus control). CI: confidence interval. N represents the total number of subjects in a two-arm trial.