The data we collect from the field may sometimes have errors and these errors vary from place to place.
Types of Errors in Demographic Data
- Sampling error of random fluctuation– in this kind of error, it is assumed that you have used the wrong techniques in the selection or collection of your data. For example, in your proposal, you might have decided to use random sampling and you ended up using a different technique or have introduce and error in your work.
- Response error or error of content- response error is very common in demography and it comes about as a result of wrong information given by the respondent. Sometimes, this wrong information given by the respondent may be deliberate or they might be given in error. Response error may also come as a result of wrong content of the questionnaire or that of researcher himself, he might have asked the wrong questions. For example a 17 year old woman having a 10 year old child.
- Error of coverage- this error comes about when certain segments of the population are left out either deliberately or purposely. In coverage there are two errors such as horizontal and vertical errors.
Horizontal errors are committed in spatial distribution. For example, in the study of soil in Jos plateau, you omitted a number of the local governments. Vertical error on the other hand could be seen in terms of social status or classes for instance, we want to categorised people according their income level or their social status e.g. rich, medium, poor and in the course of doing their censuses you omitted one social class. In this case, you have committed vertical error the following problems came about as a result of the errors observed:
- Availability of data- data may be available or not available. The data maybe absent in the study area or the data maybe lacking because no research has been carried out in such areas.
- The reliability of data- the data may not be available even though it is available because of the following: ignorance to the questions in the questionnaires. There may be protest against government regarding the course you are doing. The record kept maybe wrong. Respondents might have given wrong information. The person recording the information might have recorded wrong answers.
- Coverage- coverage is both an error and a problem. The area of study might not have been properly covered, the area may be inaccessible, the area may have poor terrain, the people might have been very hostile, the manpower to cover the probably lacking and there might have been negative altitude.