Color

Number

Cells

A single cell that doesn't contain data is called a Missing Value. In numeric columns they are denoted by asterisks, and in text columns, with blank spaces. Some commands exclude from analysis all rows with a missing value. When an arithmetic command includes a missing value Minitab sets the result to *.

Note that many users will code known missing data with "-99" or some other value to draw attention to the omission. If such values aren't recoded to blank spaces or asterisks, errors can occur in analyses that use the data.

Red

12

11

Blue

*

Green

14

TextGroup

NumGroup

Groups

Through their interaction, multiple grouping variables can result in unique cases of missing data.

By default, Minitab considers all possible combinations of group values. A group combination that includes a missing value (such as row 4) is considered a Missing Group. Additionally, Minitab recognizes the combination B 1 even though it isn't included in the worksheet. Such groups are referred to as Empty Cells.

When graphing, you can specify whether these group levels are included with Data Options > Group Options.

A

1

A

2

A

3

1

B

2

B

3