12.4  Data processing and checking for errors

Data processing refers to recording or entering your data (e.g. on to a master sheet or computer), and data checking and correcting. You may be concerned about the quality of some of the data which has been collected. For example, some of your data will probably have been collected by the volunteers who are helping you and it is possible that some may not clearly understand the objective of the data collection, and may be recording it in different ways. It is important to check your data for consistency and missing values as you collect it, and once collected, check again for errors.

No matter how carefully the data have been collected, some errors are inevitable. Errors (mistakes) can result from incorrect reading of the data, incorrect reporting, incorrect filing or incorrect typing. In addition, the data entered may be incomplete (some of the data was never collected, or has been lost). The aim of the checking process is therefore to produce a reliable set of data that you can be confident is accurate for the purposes of your analysis.

Once the data has been checked for errors and completeness, all the answers of individual respondents are entered on a data master sheet. An example is shown in Table 12.2.