# Use a repeated-measures ANOVA

**Question description**

Kotiaho et al. (2001) studied reproduction in the dung
beetle *Onthophagus taurus*. They
recorded the offspring mass and carapace length for each of three litters sired
by 12 males, and then used these measurements to construct an index called
offspring condition. Positive values of condition mean that offspring in that
litter for relatively heavy for their body size, while negative values indicate
that offspring were relatively lightweight for their body size. The average
condition scores for each litter are given below, and litters for each male are
listed in order from the first one sired to the third one sired.

Male |
1st Litter |
2nd Litter |
3rd Litter |

A |
0.82 |
0.44 |
0.92 |

B |
0.35 |
0.19 |
1.39 |

C |
0.12 |
0.84 |
0.16 |

D |
0.49 |
0.59 |
-0.23 |

E |
0.44 |
0.33 |
0.07 |

F |
0.01 |
0.29 |
0.3 |

G |
0.69 |
-0.49 |
-0.6 |

H |
0.13 |
-0.43 |
0.66 |

I |
0.21 |
-0.34 |
-0.09 |

J |
-0.35 |
-1.4 |
-0.45 |

K |
-1.04 |
-0.34 |
-0.82 |

L |
-1.27 |
-0.75 |
-0.86 |

A) Use a repeated-measures ANOVA to analyze and interpret these data.

B) Why should this be done as a repeated-measures ANOVA, rather than either a single-factor ANOVA or a two-factor ANOVA?

C) Calculate the regression equation between the condition scores of the first litter and the condition scores of the second litter, then determine if this regression slop is significantly different from zero.

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