What do the terms nominal, ordinal, ratio, interval, discrete and continuous mean and refer to?
Nominal Level - Only labels data in different categories, example categorizing as : Male or Female
Ordinal Level - Data can be arranged and ordered but difference doesnt make sense, for example: ranking as 1st, second and 3rd.
Interval Level - Data can be ordered as well as differences can be taken, but multiplication/division is not possible. for example: categorizing as different years like 2011, 2012 etc
Ratio Level - Ordering, difference and multiplication/division - all operations are possible. For example: Age in years, temperature in degrees etc.
Discrete Variable - the variable can only take point values and no values in between. For example: Number of people in a bus.
Continuous Variable - the variable can take any value within an interval, for example height of a person.