Meta-analysis data | |

Number of included effects of TMZ on U-87 MG viability | 644 |

Number of included articles the effects were reported in | 101 |

Effect of TMZ | |

Overall weighted mean effect of TMZ (U-87 MG viability reduction compared to untreated control) | 33.8% (30.0% to 37.7%) |

Investigation of heterogeneity | |

Test whether heterogeneity is present | |

Q (df=643) | 134 066.1 |

P value | <0.001 |

Total I^{2} | 99.5% |

Within-articles variance of the true effect | |

τ^{2} | 3.6% (3.2% to 4.1%) |

τ | 19.0% (17.9% to 20.3%) |

I^{2} (=proportion of total variance) | 56.6% |

Between-articles variance of the true effect (~irreproducibility) | |

τ^{2} | 2.8% (1.9% to 3.9%) |

τ | 16.6% (13.9% to 19.8%) |

I^{2} (=proportion of total variance) | 42.9% |

Random-effects three-level meta-analysis using the raw data the effects were calculated with as first level, the effect sizes within each article as second level and the articles the effects were reported in as third level. τ

^{2}: estimator of the variance of true effects (level-two variance: within-articles variance; level-three variance: between-articles variance: representant of irreproducibility); τ: square root of τ^{2}; I^{2}: proportion of within-articles and between-articles variance, respectively, of the total observed variance, including sampling error. τ^{2}estimator: restricted-maximum likelihood. Cochran’s Q was used as the test for heterogeneity using a χ^{2}distribution; values in parenthesis show CIs with significance level set at 0.05.df, degree of freedom; U-87 MG, Uppsala-87 Malignant Glioma; TMZ, temozolomide.