Levels of Measurement

In scientific research, we examine the relationships between variables. Each of these variables, in quantitative research, can be measured. Specifically, there are levels of measurement--

1) Nominal-- A nominal (sometimes called categorical) variable is one that is typically measured in categories. It is the weakest form of measurement, but sometimes the only one available. For example, if we were to identify a person as being either "male" or "female," we don't have a lot of wiggle room-- you tend to be one or the other (biologically speaking and, yes, I'm fully aware that some people are born with sex organs of both males and females). Historically, many demographic variables are nominal. These include variables such as gender, race, religion, etc.

2) Ordinal-- An ordinal variable is one where a numeric value is assigned to the variables, but we can't assume an equal distance between the points. For example, if I ask you to list your top three favorite ice cream flavors, you might say that mint chocolate chip ranks first, french vanilla ranks second, and double-dutch chocolate ranks third. Well, based on this ranking, I know that mint chocolate chip is your favorite, but I can't tell how much MORE you like it compared to the others. You may like it 10x more than your second favorite, or it may be almost a tie between the two. I have no way of knowing. Ordinal variables indicate rank, but not distance between points.

Another way of thinking of it is to look at the results of a horse race. Sometimes a horse finishes first by 20 lengths, sometimes only by a nose. In either case, the horse still wins, but, statistically speaking, the distance between points matters.

3) Interval-- An interval level of measurement provides a rank order AND equal distance between the points, but has no real "zero." The Fahrenheit scale of temperature is an every day example. The difference between 70 and 80 is the same as the difference between 20 and 30 (10 degrees). The zero on the scale, however, is not a TRUE zero, since the measurement does not indicate a lack of the concept, but, rather, just one point on the continuum.

4) Ratio-- A ratio level of measurement provides rank order, equal distance AND has a true zero-- which indicates none of the concept. For example, if I'm measuring "TV viewing" in hours for the past day and I observe that you did not watch even one moment of TV during that time, then I can record "0."

Here are some sample variables. Indicate, based on how the variables is being measured, the level of measurement:

1. What is your gender?

1. Female
2. Male
3. Other: __________

2. What color hair does the cartoon character have?

1. Blonde
2. Brown
3. Black
4. Red
5. Other: ____________

3. Indicate your level of agreement with the following statement:

College is too expensive.

5-Strongly Agree 4- Agree 3- Neutral 2-Disagree 1-Strongly Disagree


4. Please indicate total your income for the year 2009: _________________

5. Please indicate your favorite electronic media from favorite (5) to least favorite (1):

a. Internet
b. Television
c. Music
d. Video games
e. Movies

Post your answers here.

Jack