How can you modify a variable's value in SAS?

In SAS, modifying a variable's value within a data step is done by specifying the variable name followed by an equal sign and the new value. This operator assigns a new value to the variable for each observation in the dataset. For instance, if you have a variable named age and you want to change its value to 30 for each observation, you would write age = 30;. This straightforward syntax allows for efficient data manipulation within SAS, ensuring that the variable's value is updated as needed during data processing.

The other methods described do not accurately represent how SAS operates. Using a colon is not a recognized method for modifying variable values; in fact, a colon is used for different operations, such as implicit length specification or to specify formats. Changing the variable definition in the data declaration section would typically apply to new variable definitions rather than modifying existing ones. Lastly, creating a new variable with the same name and a different type is not permissible, as SAS requires variable names to be unique within a given dataset. Thus, the equal sign as a simple assignment operator remains the correct approach to modify variable values effectively.