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Direct computer entry Today, many software programs present "screens" or forms that allow for direct computer entry of data. These programs, including the free ones mentioned earlier, are quite flexible and can save a lot of time. They are help in reducing errors in entering data. You may wish to check with the computer center of your university to see what kinds of direct computer entry programs are available for your use. Cleaning data Errors creep into any operation in research. With so much detail involved, there are many opportunities for making errors in coding responses and in transferring and entering data into a computer. In transferring data for gender, for example, a 1 could easily be mistakenly entered as a 2 or the reverse. Editing or data cleaning, therefore, is an additional necessary step before analysis can begin. Fortunately, there are several ways to detect and correct errors in data preparation and entry operations. If you use a code sheet, you can scan or proof read each sheet. Examine all codes in each column to see if the codes are in the correct range. If any number other than a 1 or a 2 occurs in the field for gender (coded as 1 or 2), it is clear an error occurred. Similarly, codes for all other variables should be in an expected range. This form of eye-balling works well when the sample size is not too large. For larger samples, checking is done more easily by developing frequency distributions for each variable. (We explain what a frequency distribution is and how to construct these later in the next chapter). Some statistical analysis packages have built-in safeguards against some forms of errors. The software is told what the codes for a set of attributes should be and will "beep" to alert you when you try to enter an incorrect code. This is another benefit from using a statistical analysis package. Errors in coding and data entry can also be detected during analysis. One technique is to check whether responses to one item are reasonable in light of responses to another item. For example, when a person coded as five years old is also coded as married or as having children, you know an error occurred somewhere in the process of coding, data transfer, or in data entry. When errors are found, you need to locate and correct the error before continuing analyses. This requires going back to the source of the data and correcting each subsequent step in processing the data. Modifying data During analysis researchers frequently get new ideas and hypotheses. Testing these ideas often requires reorganization or modification of the original data. Earlier in this chapter we described one form of data modification. After we had developed a set of categories for open-ended responses, we decided to develop a new coding scheme by classifying responses as being concerned about quality of faculty versus any other kind of problem. With this new interest, we modified the data by creating a new coding scheme based on just two categories. |