# Measurement of Variables - PowerPoint PPT Presentation

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Measurement of Variables. What are the Four Types of Psychological Measures? What are the Four Measurement Scales? What are Discrete and Continuous Variables?. Types of Measures. Self-Report Tests Behavioral Measures Physical Measures. Measurement Scales.

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Measurement of Variables

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### Measurement of Variables

• What are the Four Types of Psychological Measures?

• What are the Four Measurement Scales?

• What are Discrete and Continuous Variables?

### Types of Measures

• Self-Report

• Tests

• Behavioral Measures

• Physical Measures

### Measurement Scales

• The measurement scale tells you what assumptions you can make about a score.

• Many statistics require a certain measurement scale.

• The measurement scale is a property of the data, not a decision made by the researcher.

### Nominal Scale

• Numbers classify into groups.

• Math, other than counting, is not meaningful.

• EXAMPLES:

• gender

• hair color

### Ordinal Scale

• Numbers are rank orders.

• Most mathematical operations are not meaningful.

• EXAMPLES:

• order of finish in a race

• class rank

### Interval Scale

• Numbers represent amounts, with equal intervals between numbers.

• Math, other than ratio comparisons, is meaningful.

• EXAMPLES:

• score on intelligence test

• temperature in Celsius

### Ratio Scale

• Numbers represent amounts, with equal intervals and an absolute zero

• absolute zero: zero represents complete absence

• Math, including ratios, is meaningful.

• EXAMPLES:

• number of seconds to finish

• temperature in Kelvin

### Discrete vs. ContinuousVariables

• discrete: separate, whole number values

• EXAMPLE: number of pets

• continuous: continuum including fractional values

• EXAMPLE: height

### Real Limits

• A score on a continuous variable is really an interval.

• The real limits are half a unit down and half a unit up from the measured score.

• measured score = 65 inches

• real limits: 64.5-65.5 inches