When you first add a new column to a data table, the Initialize Data menu appears in the Column Info window. Specify the type of initial data values that you want to appear in the new column. Initializing data is not available for Row State data types.
Select one of the following options:
Missing/Empty
Places missing values in the column, represented by a black dot (•) for numeric data and a blank space for character data.
Constant
Places one number or character in all of the column’s rows. Enter the number or character into the box that appears. Enter any number of characters.
Today
Places today’s timestamp in the column for each row. This option is relevant only for the Date or Time formats.
Sequence Data
Inserts sequential data based on the parameters that you specify. See Numeric or Character Sequence Data.
Random
Inserts randomly generated data values into the column. Select a method for generating the random values:
Random Integer
Enter minimum and maximum integer values. Integer values within this range are generated so that each occurs with approximately equal frequency.
Random Uniform
Enter a range for continuous values. Random uniform values within this range are generated.
Random Normal
Enter the mean and standard deviation for a normal distribution. Random normal values from this distribution are generated.
Random Indicator
Enter up to three values and corresponding desired proportions. The proportions should sum to 1. Values are generated to have a distribution that corresponds as closely as possible to the specified proportions.
Note: This method generates values in the exact proportions that you specify unless the number of rows multiplied by one of the proportions results in a fractional value.
Suppose that there are n rows and that the three proportions are p1, p2, and p3. Here is how the values are generated:
– Each row is assigned a random uniform value between 0 and 1.
– The rows are ordered according to their random uniform values.
– The rows corresponding to the smallest Round(np1) random uniform values are assigned the first value, the rows corresponding to the next smallest Round(np2) random uniform values are assigned the second value, and the remaining rows are assigned the third value.
To insert sequential data for numeric data
1. Next to Data Type, make sure Numeric is selected.
2. Next to Initialize Data, select Sequence Data.
3. In the From and To boxes, assign a starting and ending point.
4. In the Step box, assign the sequence.
5. (Optional) In the Repeat each value N times box, enter the number of times that you want each numeric value repeated.
6. Click OK.
For example, if you want the column to contain even numbers from 2 to 60, type 2 in the From box, 60 in the To box, and 2 in the Step box.
To insert sequential data for character data
1. Next to Data Type, make sure Character is selected.
2. Next to Initialize Data, select Sequence Data.
3. In the box next to Add, enter the character data and click Add.
4. (Optional) In the Repeat each value N times box, enter the number of times that you want each character value repeated.
5. Click OK.