# 4.1.2 - Two-Factor Factorial: Greenhouse Example (Minitab)

4.1.2 - Two-Factor Factorial: Greenhouse Example (Minitab)##
Minitab^{®}
– Two-Factor Factorial

For Minitab, we also need to convert the data to a stacked format (Lesson4 2 way Stacked Dataset). Once we do this, we will need to use a different set of commands to generate the ANOVA. We use...

`Stat` > `ANOVA` > `General Linear Model` > `Fit the General Linear Model`

and get the following dialog box:

Click on the `Model` box (arrow above), hold down the shift key and highlight both factors. Then click on the `Add` box to add the interaction to the model.

Following the ANOVA run, you can generate the mean comparsons by

`Stat` > `ANOVA` > `General Linear Model` > `Comparisons`

Specify the* fert*species* interaction term in the Terms box for the comparisons, and check the Comparisons box.

This will produce the same ANOVA output as SAS (not shown here), and in addition gives the following table of mean comparison results:

fert | species | N | Mean | Grouping |
---|---|---|---|---|

f3 | SppB | 6 | 35.1 | A |

f1 | SppB | 6 | 31.6 | B |

f2 | SppB | 6 | 30.0 | B |

f3 | SppA | 6 | 29.2 | B C |

f1 | SppA | 6 | 28.6 | B C |

f2 | SppA | 6 | 25.9 | C D |

control | SppB | 6 | 23.7 | D E |

control | SppB | 6 | 21.0 | E |

Means that do not share a letter are significantly different.

We can take these out to Excel to make our final graph.