You can control how missing values and empty cells are graphed, in
the graph creation dialog box.

In the following worksheet, the two grouping variables Style and Size each have three values. However, some data are missing.

C1-T | C2-T | C3 |
---|---|---|

Style | Size | Quantity |

Short | Small | 4 |

Short | Medium | 6 |

Short | Large | 3 |

Long | Small | 3 |

Long | Medium | 7 |

Long | Large | 2 |

Small | 5 | |

Hooded | Small | 1 |

Hooded | Medium | 4 |

- Missing group
- One row contains a missing value in the Style column with Small in the Size column. This set of data is considered a "missing group".
- Empty cell
- The group Hooded/Large does not appear here. This combination is considered an "empty cell". You can exclude empty cells to save space on your graph, or to show that the group does not exist.

By default, Minitab treats missing group names as a separate group. For
example, rows 2 and 4 in the following worksheet contain missing values instead
of A or B. The interval plot includes a separate group for these rows. (Because
the group name is missing for these rows, the tick mark label is also missing.)

C1-T | C2 |
---|---|

Group | Data |

A | 22 |

30 | |

B | 47 |

25 | |

... | ... |

To exclude groups that have missing names when you create the graph,
complete the following steps:

- Click Data Options.
- On the Group Options tab, deselect Include missing as a group.

By default, Minitab includes all possible groups on a graph, including
groups that have no data. For example, the following bar chart includes a tick
mark for group A2, but no bar. A2 is an empty cell because no worksheet rows
contain an A in column C1 and a 2 in column C2.

C1-T | C2 | C3 |
---|---|---|

Group | Subgroup | Data |

A | 1 | 55 |

B | 1 | 41 |

B | 2 | 29 |

C | 1 | 44 |

C | 2 | 33 |

To exclude empty cells when you create a graph, complete the following
steps:

- Click Data Options.
- On the Group Options tab, deselect Include empty cells.

- Double-click the graph.
- Double-click the scale to open the Edit Scale dialog box.
- On the Scale tab, deselect Include empty cells.

The following examples graph data from the previous worksheet to show all possible combinations.