"Qualitative" is usually opposed to "quantitative". But consider the following sentence:

Varying the CO2 emissions in climate models has a qualitative effect on the predictions of future weather conditions.

Could "qualitative" also mean "significant" in this context?

I think I have seen several examples of this kind, where the word "qualitative" is used even when the effects have been quantified. Since it is in the field of research, I wonder if the meaning could really be "significant" sometimes, or if it is just due to the tendency of researchers to stay very careful about the meaning of the results they find.

  • 1
    So, what is the definition of "qualitative"?
    – Hot Licks
    Nov 30, 2015 at 2:56
  • 3
    The "qualitative effect" is "on the predictions". One quality of predictions is reliability; another is accuracy. The qualitative effect could be to increase or decrease the accuracy or reliability of the predictions. Without more context, I'm unable to determine which quality or what effect.
    – JEL
    Nov 30, 2015 at 3:41

4 Answers 4


Qualitative means pertaining to or concerned with quality or qualities.

So a "qualitative change" must be changing one or more "qualities" of the system being discussed.

So, what is a "quality" associated with weather?

A "quantity" associated with weather may be average daily temperature or humidity, or annual rainfall. While massive changes in these quantities can usually bring about significant effects on those living in an area, small changes generally do not.

A "quality" associated with weather may be whether the climate is considered tropical or arid or oceanic, whether the area is subjected to severe storms, etc. Such "qualitative" changes would very often have serious effects on those living in the area.


The qualitative differences produced by different rates of CO2, and when the rate is seasonal, or constant, or cumulative, are:

.1.Positive feedback loops, for instance when CO2 creates a hotter Summer which means that the the Oceans can't absorb the gasses so fast, and plant rubbish rots faster,

.2.Negative feedback loops, for instance when plants grow faster and take up more CO2,

.3.Instability. for instance the intermittent El Nino current, & the upper air Jet Stream.

With all this happening the varying rates produce different sorts of patterns, and different types of interactions; that is what is qualitative.

@JEL states it in one sentence, in the comment above.


oops, I read that as quanititative...

A quantitative effect is an effect that can be measured. An important concept of measuring something is called significant figures. This concept has to do with the precision that one can measure something.

I'm not going to go into detail about what significant figures means here. Just to say that if your ruler has marks every 1/16th inch, then any distance less than 1/32nd is insignificant.

So, there is a relationship between "quantitative" and "significant", and that might be the reason it popped into your head. Whether or not the measurement is significant depends on how much you care.

  • I believe the OP is looking for a relationship between quaLitative and significant (not "quanTitative"). But I like the sig-figs comparison.
    – Nonnal
    Nov 30, 2015 at 4:51
  • @Nonnal, I see that now. Now I'm wondering why the paper used the word "qualitative".
    – Carl
    Nov 30, 2015 at 4:57

Having a qualitative effect means prompting an increase in quality, no more and no less.

That said, that kind of phraseology is misleading, confusing, and ultimately nonsensical. It's a way to pile up lots of scientific-sounding words without actually stating a damn thing. Boring the audience to death while asking for more grants, hoping they'll think "He's pretty smart. We don't understand what the hell he's saying, but he probably knows what he's talking about, so let's give him some money for further research."

I, too, have seen many examples of this kind, and each new example I encounter only makes me loathe them more.

Lastly, your sample sentence doesn't make any sense. Predicted future weather conditions? Really? A qualitative effect on conditions that have already been predicted? Goodness.

  • So what is the definition of "qualitative"?
    – Hot Licks
    Nov 30, 2015 at 3:00
  • @HotLicks: The dictionary says it's "pertaining to, or concerned with, quality or qualities." What did you think it was? "Pleasurable"?
    – Ricky
    Nov 30, 2015 at 3:02
  • And what is a "quality"?
    – Hot Licks
    Nov 30, 2015 at 3:03
  • @HotLicks: Look it up, Socrates.
    – Ricky
    Nov 30, 2015 at 3:07

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