### Re: What defines a Quantitative and a Qualitative Observation?

Date: Thu Feb 4 16:00:28 1999
Posted By: Raymond Cheong, Undergraduate, Chemical Engineering, University of Maryland
Area of science: Chemistry
ID: 917676272.Ch
Message:

Hello Scott,

You have asked a very important question. Science is based on observations and the repeatability of observations. If I were to check your observations, we need a common ground in order to compare what we each observe individually. That is, we need descriptive language.

Observations are generally quantitative or qualitative, but there is some gray area (e.g. semiquantitative). Let's start with a dictionary definition (Merriam Webster Online):

Quantitative: 2. of, relating to, or involving the measurement of quantity or amount

Qualitative: 1. of, relating to, or involving quality or kind

OK, we see that a quantitative observation involves a quantity, a number. Here are some examples: humans have 10 fingers, the speed limit is 55 miles per hour, class is 1 hour long, acceleration due to gravity is 9.8 m/s^2. These are all numbers, and usually with units to give them physical significance. These observations are quantities and the units are understood.

Qualitative observations are not as precise: I have many fingers, the speed limit is fast, class is long, acceleration due to gravity is large. They are descriptive adjectives, but you have to "qualify" what you mean; for example, class is long compared to (fill in blank). Otherwise, my long and your long are totally different.

Here are some more examples:

 Qualitative Quantitative red 700 nm wavelength far from the earth 300 million light years microscopic smaller than 1 um burns quickly burns at 1 cm candle per minute hot 350 degrees C

I hope this gives you a sense of qualitative and quantitative. Search the MADSci archives for these two terms for more examples. Just remember that these are ways of describing observations and that quantitative is more precise language.

Thanks for the good question. I hope that you are enjoying your science classes.

Raymond Cheong

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