Question by Tommy: What is the difference between ordinal data and interval data?
The book says that ordinal can be used to rank or order individuals or groups, but it can NOT be used to determine how much of a difference exists between individuals. It gives the examples of percentile rankings on standardized tests and place finishes in a race.
I don’t understand why these numbers can not be used to determine the difference between individuals. Isn’t the percentile ranking and place finish in a race used exactly for the purpose of comparing one performance against another? If someone finished 3rd in a race, and someone else finished 8th, the difference in their places is 5.
It says you CAN use interval numbers to determine differences between individuals based on some trait or characteristic. Interval numbers are defined as being consecutive. It gives the examples of numbers on the Fahrenheit scale as an example.
I think the part I’m confused about is the difference between ranking and telling differences between individuals.
Best answer:
Answer by Doctor Q
Ordinal data just tells you the order of something. i.e. think of a 100m race.
1st place might take 10 secs, 2nd might be 10.5 secs and 3rd could be 11.09 secs.
The interval times between them are not fixed. Ordinal data just provides the position of where they came.
Interval data provides information which is more quantative. On the temperature scale you mention, 10 degrees Farenheit and say 11 degrees Farenheit – the difference is 1 degree…. the interval between each is the same – the scale is uniform!!
Ordinal – scale not uniform
Interval – scale is uniform
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