As a matter of fact, editing involves a careful scrutiny of the completed questionnaires and/or schedules. Miscellaneous and exceptional items, if any, should be usually placed in the last row of the table. Data Processing Operations. How may classes should be there? Similarly, percentages and/or averages must also be kept close to the data. Classification according to attributes: As stated above, data are classified on the basis of common characteristics which can either be descriptive (such as literacy, sex, honesty, etc.) R = Range (i.e., difference between the values of the largest item and smallest item among the given items);