# Thread: Example(s) of an interval scale

1. ## Example(s) of an interval scale

Temperature in Fahrenheit or Celsius is almost always used as the example of an interval scale. Another one is Year (e.g. birth year) although one could argue that not every year has the same amount of days and therefor the difference between two consecutive years is not exactly the same.

The definition I'm using for interval would be that the values should have equal differences and there zero point is chosen somewhat arbitrary (e.g. 0 on the scale does not mean the absence of the underlying property that is being measured).

This means that any non-linear scale cannot be interval since it would violate the 'equal intervals' part. IQ is sometimes used as an example of interval, but that actually does not have equal intervals.

I've tried googling for other examples of an interval scale but couldn't find any (at least not on the first five pages of hits), or found they use a different definition.

Does anyone have any other examples of an interval scale that fits the definition the way I use it?

2. ## Re: Example(s) of an interval scale

Does anyone have any other examples of an interval scale that fits the definition the way I use it?
The water level on the river Nile (or whatever river that is close to you).

(Some people say that the temperature scale is a ratio scale, since there is an absolute zero point. Also time had a zero point at the 'big bang'.)

3. ## The Following User Says Thank You to GretaGarbo For This Useful Post:

blubblub (04-21-2016)

4. ## Re: Example(s) of an interval scale

Originally Posted by GretaGarbo
The water level on the river Nile (or whatever river that is close to you).

(Some people say that the temperature scale is a ratio scale, since there is an absolute zero point. Also time had a zero point at the 'big bang'.)
Thanks for the reply. Interesting example the water level. For sure it is linear, only wondering about the zero point. A water level on river x of 0 would mean the absence of water, so wouldn't that make it ratio?
EDIT: However I'm all of a sudden thinking of NAP, which is probably really an arbitrary zero chosen as the average sea level (while they could also have chosen the median sea level, or the mean river level, or....).

Interesting comment about the temperature. One could argue that theoretically there is no true zero as in there is Always a temperature, so a temperature of 0 will Always depend on how you define temperature. Celsius used the boiling point of water as 0 (which later got flipped to the freezing point), Fahrenheit something with brinc if I'm not mistaken and Kelvin the speed molecules move (and with it the absence of speed as 0) (Note that I'm no physicist but roughly I think these descriptions are okay) So Kelvin would be a ratio scale.

Taking the big bang as 0 and something else constant to measure time would perhaps indeed be ratio, however we need to be certain then there really was nothing (and also not nothing) pre-big bang, something that I think is still debated.

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