2.1.13 Editing primary and secondary data
Once data have been obtained either from primary or secondary source, the next step in a statistical investigation is to edit the data, i.e., to scrutiny the same. The main objective of editing is to detect possible errors and irregularities. The task of editing is a highly specialized one and requires great care and attention. Negligence in this respect may render useless the findings of an otherwise valuable study. However, it should be noted that the work of editing data collected from internal records and published sources is relatively simple – it is the data collected from a survey that need extensive editing.
While editing primary data the following considerations need attention:
1. The data should be complete.
2. The data should be consistent,
3. The data should be accurate, and
4. The data should be homogeneous.
1. Editing for completeness. The editior should see that each schedule and questionnaire is complete in all respects, i.e., answer to each and every question has been furnished. If some questions have not been answered and those questions are of vital importance the informants should be contacted again either personally or through correspondence. It may happen that in spite of best efforts a few questions remain unanswered. In such questions, the editor should mark ‘No answer ’ in the space provided for answers and if the questions are of vital importance then the schedule or questionnaire should be dropped.
2. Editing for consistency. While editing the data for consistency, the editor should see that the answers to questions are not contradictory in nature. If there are mutually contradictory answers, he should try to obtain the correct answers either by referring back the questionnaire or by contacting, wherever possible, the informant in person. For example, if amongst others, reply to the questions: (a) Are you married? (b) Mention the number of children you have, and the are respectively ‘no’ and to ‘three’, then there is a contradiction and it should be clarified.
3. Editing for accuracy. The reliability of conclusions depends basically on the correctness of information. If the information supplied is wrong, conclusions can never be valid. It is, therefore, necessary for the investigators to see that the information is accurate in all respects. However, this is one of the most difficult tasks of the investigators. If the inaccuracy is due to arithmetic errors, it can be easily detected and corrected. But if the cause of inaccuracy is faulty information supplied, it may be difficult to verify it, e.g., information relating to income, age, etc.
4. Editing for uniformity. By homogeneity we mean the condition in which all the questions have been understood in the same sense. The investigators must check all the questions for uniform interpretation. For example, as to the question of income, if some informants have given monthly income, others annual income and still others weekly income or even daily income, no comparison can be made. Similarly, if some persons have given the basic income whereas others the total income, no comparison is possible. The investigators should check up that the information supplied by the various people is homogeneous and uniform.