Posted by Rhea on Wednesday, September 29, 2010 at 11:40am.
Is the following classified as interval, ordinal or nominal data?
The marks achieved by the students in a statistics course out of 100.

Statistics  bobpursley, Wednesday, September 29, 2010 at 12:06pm
One would hope the grades are interval.

Statistics (correction)  PsyDAG, Thursday, September 30, 2010 at 2:18pm
Hoping isn't enough.
The intervals are not necessarily equal. In other words, the difference between 1040 would not necessarily mean the same as the difference between 60100. The scale is only ordinal. All you can say for sure is that a higher score indicates greater knowledge of statistics, and a lower score indicates less.
I. Nominal scale names or classifies only (social security number, baseball, football examples).
II. Ordinal scale — also ranks beside naming (height, baseball standings, beauty pageant examples). Most tests are only ordinal scales.
III. Interval scale — beside previous qualities, also has equal intervals and an arbitrary zero (centigrade/Fahrenheit thermometer examples).
IV. Ratio scale also has a true/absolute zero, which allows comparisons in terms of ratios (Kelvin thermometer, height/weight measurements). Math uses ratio scale.
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