Problem: Qualitative or Quantitative?

It is desirable for the experimenter to reflect on what kind of inputs and outputs he is likely to deal with in the proposed research problem. Is he going to deal with qualities or properties known to have been measured, or is he left to deal anew with qualities whose measurement is not well established? A little digression may be necessary to show the relation between quality and quantity, or more precisely, what we may call qualitative and quantitative research.

In the statement “Michael is tall,” being tall is a quality that Michael has. The quality here is given by the adjective “tall.” But the statement, being relative, lacks precision. If the Michael referred to is one of the NBA players, he could be 6’6″, or in that range. If, instead, Michael is a fourth grader in a local school, he could be only 4’4″, and still the statement is proper. The use of the word “tall” is relative, ambiguous, and nonspecific. If, instead, the statement is “Michael is 6’6″,” we understand that he is taller than quite a few men who are not basketball players, but not the tallest NBA player. Here the tallness is quantified. There is no room for ambiguity. Michael’s height can still be compared with that of others, but with specifics such as “three inches shorter than Kareem” or “two inches taller than John.” There are many statements in routine usage where a qualitative statement, such as “George is rich,” “The rose is red,” or “You are late to work,” is quite adequate. The degrees of George’s richness or the rose’s redness or your lateness are not quantified. In the last men­tioned instance, whether you walked into the office a second later or an hour later than you were expected to be in, the remark that you are late to work is equally correct. Needless to say, statements with quantities are preferable in experiments, for with those, you know where you stand.

To go a step further, there are qualities that can be quantified, like degrees of tallness (the height of a person), lateness (so many minutes past an appointed hour), or hotness (the temperature of an object). What is common in all these examples is that these qualities are measurable. By contrast, in the statements “Helen is beautiful,” “This fruit is delicious,” or “This rose is red,” we can­not measure the quality of beauty, taste, or redness. These are cer­tainly qualities we can recognize and distinguish, but there are no procedures for, and no units of, measurement. In summary, we may say that not all qualities are measurable. In terms of measur­ability, we may distinguish two classes of qualities: those that can and those that cannot pass the criteria of measurability. It should be noted, however, that criteria not currently available may in the future be developed and accepted as normal, and new procedures for their measurement may come to be accepted as “standard.”

It is very important for the experimenter presented with a problem to know what kinds of qualities or properties he is expected to deal with. If they are measurable qualities, his task is reduced to one of identifying the procedure and equipment needed for measurement. He must address whether such equip­ment is available on the market or he must devise his own, what range of variation is involved, what degree of accuracy is required, and so on. If, on the contrary, he expects to encounter qualities or properties that are not measurable by any currently known procedures with appropriate equipment, he should be candid with himself and with others, and declare that the prob­lem is not worth proceeding with.

Source: Srinagesh K (2005), The Principles of Experimental Research, Butterworth-Heinemann; 1st edition.