What abstract, broad ideas interest us?

Examples: self-esteem, aggression, prejudice, gender roles, dissonance

How can we measure them?
 

Operational Definitions

We measure variables by coming up with operational definitions

The more specific, the better

Multiple ways to operationally define a conceptual variable is ideal
    - converging operations
 

Conceptual                    Operational

Attraction                                 Do P's ask for female confederate's phone #?
Self-Esteem                             P's response time to positive self-descriptors
Prejudice                                  Do P's mail "lost" letters addressed to NAACP?
Pro-Social Behavior                P's reported donations to charity in the past year
Intelligence                              P's scores on a standardized IQ test
 

Variable Measurement

Nominal variables are categorical

I want to know what type of high school Pís attended:
    1 = public
    2 = private, secular
    3 = private, religious
 
The number assignments are arbitrary and nonmathmetical
 

Quantitative Variables

Numbers are not arbitrary

Three types:
    Ordinal
    Interval
    Ratio

Mnemonic Tip: NOIR
    * Each one is more mathematical/sophisticated than the previous one
 

Ordinal Variables

Includes most scales used in social psych
    * There is meaning to the numbers, as 2 is greater than 1, 3 is greater than 2, etc.
    * But the interval between numbers is not standardized

Ordinal variables tell us order, but not relative distance
 

Interval Variables

Again, these tell us about order
Scales have standardized differences between numbers
    Example: IQ
        - The difference between 100 and 110 represents the same difference as between 140 and 150
        - But the midpoint of 100 is arbitrary
        - There is no absolute zero; an IQ of 140 does not mean you are twice as smart as an IQ of 70
 

Ratio Variables

These scales do have an absolute zero
    Example: Money
        - The difference between $6 and $5 is the same as between $113 and $112
        - Also, unlike an interval scale, you can say someone with $140 has twice as much as $70
        - $0 is an absolute lack of money
 

Why do we care?

Different statistical techniques appropriate for different types of scales

Determines what we can do to the data
    - Ratio data can be multiplied, divided, averaged, etc.
    - Makes no sense to multiply or average nominal data!
 

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