Is IQ interval or ratio data?

Answer 1

While IQ itself is a ratio", the data is interval-level data.

The IQ was first created in order to relate the mental development of a child to the child's chronological age the IQ. IQ = (MA/CA) * 100

While in theory, a birth one has a MA of 0, so one could make a theoretical argument that IQ data is a ratio level of measurement because it has a natural zero. The fact is, nobody ever deals with 0 IQ because there is no such test for babies. So while theoretically, scores can range any amount below or above 100, but in practice they do not meaningfully go much below 50.

Remember a ratio level of measurement is the same as an interval level of measurement with the additional property of a natural zero, where zero indicates none of the quantity is present. We use it for things like distances and prices.

If we do not travel at all, that is zero distance and a free item has a 0 price.

On the other hand, interval level of measurement allows the data to be arranged in some order and the difference between any two data values is meaningful. Some common examples are body temperature, and years. Years is confusing but time 0 is arbitrary and not really a starting point of time. Also the value of 0 is arbitrary for temps and does not indicate any true absence of heat.

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Answer 2

Interval

Answer 3

interval