In the variable 'ChurchGoing' (dem84), in the WatchAndListenSurvey.sav database, measurements are taken of how often people go to church. When you calculate a measure of central tendency for this variable, it gives information about all the respondents, including those who answered 'no answer' or 'not applicable'. Before doing the exercises below, you first have to list these options as 'missing values' in SPSS.

a. What percentage of the respondents goes to church once a month or less?

b. What is the level of measurement of this variable?

c. What conclusion can you draw? When giving your answer, you must include the following: the 'content' of the variable, the units of analysis, the correct number for the measure of central tendency (round off to two decimals), and the interpretation of the measure of central tendency.

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1 Determining the level of measurement of a variable Nominal scale In a nominal scale, the characteristics are assigned a random value. The sequence of the characteristics does not matter, as can be seen on the scale below. Moreover, the distance between the letters themselves has no real meaning.

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Ordinal scale In an ordinal scale, the characteristics are not assigned a random value, but the scale shows their rankings. This can be seen on the scale below. The values are in alphabetical order. The distance between the letters remains random, however, and without any real meaning.

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Interval scale In an interval level of measurement, the scale indicates a sequence. The distance between the letters themselves also has real meaning. For example, the difference between '2' - '1' = '4' - '3' and the distance '3' - '2' = '5' - '4'. However, there is no zero point. An example of an interval scale is the temperature in degrees Celsius. The difference in temperature between 5 and 10 degrees Celsius is the same as that between 35 and 40 degrees. However, the zero point is random - in other words, 0 degrees Celsius is not the lowest possible temperature. This means that you cannot say that 40 degrees Celsius is four times greater than 10 degrees Celsius, because the relationships between two numbers are not the same (because of the lack of identical distances, and a natural zero point).

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Ratio scale The ratio scale has all the same characteristics of an interval scale. But it also has a natural zero point (0). This means that the differences between the numbers on the scale have a real and identical meaning, as does the relationship between two numbers. Therefore, you can say that a person who has four children has twice as many children as someone who has two.

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2 Measures of central tendency and measures of dispersion selection chart

SPSS exercise 2.7

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