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Table 17.1. Illustrative tally sheet
By adding this category, the N for each analysis will be the same and should equal the N for the sample. Without the "no data" category, the N could vary from one analysis to another and you won't know if you made a mistake in tallying or whether the difference was due to missing data. By adding the "no data" category, the N should always equal the N for the sample. If the N for some item does not equal the N for the study, you will know you have made a mistake in tallying and will have to correct it before going on. Tallying numbers Data in the form of numbers are tallied by placing a tally mark after each number as it occurs. To illustrate, imagine you had to tally responses for the following item: "How old is the head of this household?" Let's say the youngest head of a household was 18 and the oldest was 84 years of age. You could list each age that was reported and then place a tally after each age as it occurred. The result would be a long list of numbers (ages), each followed by so many tally marks and a number representing the frequency for each age. There is a better way, however, to present numbers that cover a wide range, such as the age distribution we are examining. Ages can be combined or grouped into intervals. An interval is simply some span of numbers used to represent age or any other continuous variable. Generally, at least 3 and not more than about 10 or 15 intervals are used for most numerical variables. Also, the intervals have to be mutually exclusive and exhaustive, just as was required for the creation of nominal or ordinal measures. Finally, in creating intervals it is useful to use a span that corresponds to general usage. For intervals based on age, 5 or 10 year intervals are commonly used. Intervals for income might be in terms of hundreds or thousands of some currency. To illustrate this process, Table 17.2 shows tallying in terms of 10-year intervals. Notice that the two extreme categories are left open to achieve the criterion of exhaustiveness. For each head aged 19 or younger, for example, a tally mark would be placed after that interval each time a man was 19 or younger. In the same way, tally marks are made for each man 60 years or older. The same procedure would be followed in recording the age of each head aged 20-29, 30-39, etc. As a check, the tallies are converted to frequencies, as shown in the column to the right, and then added. The total should equal the N for the analysis. Table 17.2. Tally sheet for ages grouped by ten-year intervals
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