In the case “Creatinine Levels in Hospitalized Patients,” the data file CreatinineLevels.jmp was prepared for analysis and an indicator variable was added to identify those patients with creatinine levels greater than 2. A best practice is to document all columns in a data file either directly in the file or in a codebook. This includes both source and derived data (new variables created from source data). A properly annotated data file is a valuable reference useful throughout the data analysis and reporting process.

The JMP Notes feature allows documentation to be added to the columns in a data table. To document the addition of the column “Creatinine > 2” right click the column header and select Column Info. From the Column Properties drop-down menu select Notes. This will open a field where information can be added about this column. An example is shown in Figure 7.1 Adding a Note to a Column.

Including this type of documentation is consistent with the practice of creating reproducible research (American Statistical Association, 2017).