Frequently, you use worksheets that are already created for you. However, sometimes you must enter or import data into a Minitab worksheet before you start an analysis.
After your data are in Minitab, you might need to edit cells or reorganize columns and rows to prepare the data for analysis. Some common manipulations are stacking, subsetting, specifying column names, and editing data values.
In this chapter, you import data into Minitab from different sources. You also learn how ShippingData.MTW was prepared for analysis.
To analyze all the shipping data, open each file in Minitab, then stack the files into one worksheet.
Start with the data from the Eastern shipping center.
The Central shipping center data are in an Excel spreadsheet. You can open Excel files in Minitab.
The Western shipping center data was in a text file. You can open text files in Minitab.
Notice that the worksheets for the shipping centers have the same column names. To make the data easier to analyze, you need to combine the data into one worksheet by stacking columns that have the same names. You can move data by copying and pasting or by using commands on the Data menu.
The Source column contains the labels that identify data from the shipping centers. Move the Source column to C1, and rename the column Center.
For a complete list of the data manipulations that are available in Minitab, go to Data menu in the Minitab Help index. To access the Minitab Help index, open Minitab, choose , then click the Index tab in the left pane.
Some of the labels in the Center column include a file extension. Recode the labels to remove the file extension.
The labels in the Center column are now Eastern, Central, and Western.
Before you save your new worksheet and perform analyses, you need to calculate the number of days that elapsed between order dates and delivery dates. You can use Minitab’s Calculator to assign a formula to a column to calculate these values. If you change or add data, the calculated values are automatically updated.
Insert a column between Arrival and Status.
Use Minitab’s Calculator to perform basic arithmetic or mathematical functions. Minitab stores the results in a column or a constant. You can assign a formula to a column so that the calculated values update automatically if the data change.
Calculate the delivery time and store the values in the Days column.
You can also add a formula to a column by selecting the column and choosing.
For more information on formulas in columns, go to Formulas in the Minitab Help index. For more information on Minitab’s Calculator and the available operations and functions, go to Calculator in the Minitab Help index. To access the Minitab Help index, open Minitab, choose , then click the Index tab in the left pane.
The Days column contains the calculated values that represent delivery time. These values are expressed in number of days. When you assign a formula to a column, a status indicator appears in the upper right corner of the column heading on the worksheet. This indicator specifies whether the formula is properly defined and whether the data need to be updated by re-calculating the values. A green check mark indicates the data are up-to-date.
Hold the pointer over the status indicator to view the formula assigned to the column. Double-click the status indicator to edit the formula.
Suppose you learn that the arrival date for a shipment in the Central shipping region is incorrect. If you correct the date in the worksheet, Minitab automatically updates the Days column.
Update the arrival date in row 127.
If you prefer to update formulas manually, then chooseto deselect this option. If values in the worksheet change and cause the formula in a column to be out of date, the status indicator for that column changes to a yellow triangle. Choose to update all formulas in the project.
Save all your work in a Minitab worksheet.
The shipping center data from several sources are in Minitab and are set up properly for analysis. In the next chapter, you adjust Minitab default settings to make future analyses easier.
Go to Customizing Minitab.