mjl1717
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Whats the difference between nominal and ordinal variables,and when are they used?
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| Meghna
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Variables can be qualitative or quantitative.
Qualitative variables can be nominal and ordinal.
A nominal variable is one which can take a range of values that cannot be arranged into any particular order. For example, you might want to know what types of medication a group of hypertensive patients were taking before entry to a study, and classify them according to whether they were taking calcium-channel blockers, diuretics, beta-blockers, or ACE inhibitors. We now have a variable with four categories, but there is no order to the categories. For example, it would be meaningless to say that diuretics are greater than ACE-inhibitors which in turn are greater than beta-blockers. Other examples are gender, marital status.
An ordinal variable is one where the possible values of the variable can be placed in a meaningful order. An example would be an assessment of whether some symptom had improved, worsened, or stayed the same. Or staging of cancer.
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| mjl1717
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Thx- I like how you defined nominal, but I just want to say key words for ordinal are "rank order" eg. class rank in med school, or olympic medals For starters chi square uses any # of nominal variables.
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