lec5 - Chapter 5 Standardized Measurement and Assessment...

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Chapter 5 Standardized Measurement and Assessment (For the concept map that goes with this chapter, click here. ) Defining Measurement When we measure, we attempt to identify the dimensions, quantity, capacity, or degree of something. Measurement is formally defined as the act of measuring by assigning symbols or numbers to something according to a specific set of rules. Measurement can be categorized by the type of information that is communicated by the symbols or numbers assigned to the variables of interest. In particular, there are four levels or types of information are discussed next in the chapter. They are called the four "scales of measurement." Scales of Measurement 1. Nominal Scale. This is a nonquantitative measurement scale. It is used to categorize, label, classify, name, or identify variables. It classifies groups or types. Numbers can be used to label the categories of a nominal variable but the numbers serve only as markers, not as indicators of amount or quantity (e.g., if you wanted to, you could mark the categories of the variable called "gender" with 1=female and 2=male). Some examples of nominal level variables are the country you were born in, college major, personality type, experimental group (e.g., experimental group or control group). 2. Ordinal Scale. This level of measurement enables one to make ordinal judgments (i.e., judgments about rank order ). Any variable where the levels can be ranked (but you don't know if the distance between the levels is the same) is an ordinal variable. Some examples are order of finish position in a marathon, billboard top 40, rank in class. 3. Interval Scale. This scale or level of measurement has the characteristics of rank order and equal intervals (i.e., the distance between adjacent points is the same). It does not possess an absolute zero point. Some examples are Celsius temperature, Fahrenheit temperature, IQ scores. Here is the idea of the lack of a true zero point: zero degrees Celsius does not mean no temperature at all; in a Fahrenheit scale, it is equal to the freezing point or 32 degrees. Zero degrees in these scales does not mean zero or no temperature.
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4. Ratio Scale. This is a scale with a true zero point. It also has all of the "lower level" characteristics (i.e., the key characteristic of each of the lower level scales) of equal intervals (interval scale), rank order (ordinal scale), and ability to mark a value with a name (nominal scale). Some examples of ratio level scales are number correct, weight, height, response time, Kelvin temperature, and annual income. Here is an example of the presence of a true zero point: If your annual income is exactly zero dollars then you earned no annual income at all. (You can buy absolutely nothing with zero dollars.) Zero means zero. Assumptions Underlying Testing and Measurement
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This note was uploaded on 07/26/2011 for the course EDE 4942 taught by Professor Staff during the Spring '11 term at University of Florida.

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lec5 - Chapter 5 Standardized Measurement and Assessment...

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