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Psychophysical scaling

Absolute threshold

Difference threshold

Thurstone scale

Thurstone scaling

Write as many statements as possible.

Knowledgeable judges rank them.

Give average score of ranks.

Choose items that represent range

Method of equally appearing intervals

Thurstone adv/dis

Advantages

Get latitudes of acceptance

Can see if attitude is consistent

Disadvantages

Hard to construct

Judges attitudes influence ratings.

Less reliable than Likert

Psychometric scaling

Guttman scale (cumulative scale)

Advantages:

one score gives lots of info

unidimensional

Disadvantages

unidimensional

Coefficient of reproducibility

Likert scale (summated rating scale)

Coefficient of correlation

Psychometric scaling

Likert scale (summated rating scale)

Advantages

Easy to construct

Can be multidimensional

More reliable than Thurstone

Participants like it

Disadvantages

Doesn’t give info on latitudes of acceptance

Doesn’t give all info with one number

Coefficient of correlation

Validity

Criterion-related validity

Predictive validity

Concurrent validity

Construct validity

Face validity

Convergent validity

Divergent validity

Validity

Problems with construct validity

Demand characteristics

Social desirability

Internal validity

External validity

Reliability

True score + measurement error

Test-retest

Alternate forms

Internal consistency reliability

Split-half

Odd-even

Item-total

Measurement properties

Difference

Magnitude

Equal intervals

True zero

Types of scales

Nominal

Ordinal

Interval

Ratio

Why should you care?

More properties mean more information

Affects the stats you can do

Helps you evaluate research

What types of scales are these?

Jan. 1, 2000

number of presses a rat makes in an hour

third place in a fiction contest

zip code

being a junior in college