Measurement: error, reliability, validity and scales of measurement

Question 1

Measurement error

Answer 1

When collected data says one thing but in actuality it is another.
* Random error
* Bias

observed score= true score + measurement error

Question 2

Reliability

Answer 2

The overall consistency of a measure.
* Test-Retest Reliability
* Internal Consistency

Question 3

Validity

Answer 3

Extent to which a measure is truthful.
* Content Validity (measure sufficiently covers intended areas)
* Construct Validity (accurate measurement tool)
1. Convergent validity: does the scores on the measure agree with other related constructs
2. Discriminant Validity: discriminates against unrelated measures

Question 4

Levels of measurement

Answer 4

• Nomainal- levels are only named
• Ordinal- levels can be ranked
• Interval- there is a set numerical difference between each pair of levels (no zero)
• Ratio- meaningful zero