Example of formatting cells that contain missing observations

A quality engineer for a pharmaceutical company wants to determine the shelf life for pills that contain a new drug. The engineer collects a batch of pills from each of five production lines. The engineer tests one pill from each batch at nine different times. However, the engineer fails to test a sample at some of the production line/time combinations. Therefore, those observations are missing.

The engineer uses conditional formatting to identify the cells that contain the missing observations.