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 10-40 would not necessarily mean the same as the difference between 60-100. 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.