Chapter 4

Data Collection, Assessment, Methods, and Measurement Strategies

Measurement

- a process through which researchers describe, explain, and predict the phenomena and constructs of our daily existence.
- enables researchers to quantify abstract constructs and variables
- level of sophistication used to analyze data derived from a study is directly dependent on the scale of measurement used to quantify the variables of interest

Categories of data:

Nonmetric

- qualitative

Metric-

quantitative

Scales of Measurement:

Nominal scales

- only used to qualitatively classify or categorize
e.g.: place of birth, religious affiliation

Ordinal scale

- measures a variable in terms of identity and magnitude (also qualitative in nature)
e.g.: finishing positions of runners in a race

Interval Scale

- builds on ordinal measurements by providing information about both order and distance between values of variables. There is no absolute zero.
e.g.: Fahrenheit/ Celsius scale (although there is a 0, it does not represent and absence of tempertature)

Ratio Scale

- same as interval but with an absolute 0.
e.g.: money

Reliability

- consistency or dependability of a measurement technique

Assessing Reliability

Test-retest reliability

- stability of test scores over time and involves repeating the same test on at least one other occasion.
Split-half reliability- administration of a single test that is divided into two equal parts

Alternate-form reliability

- expressed as the correlation between forms of the same measure where the items on each measure represent the same item content and construct

Interrater reliability

- used to determine the agreement between different judges or raters when they are observing or evaluating the performance of others.

Content Related Validity

- the relevance of the instrument or measurement strategy to the construct being measured

Construct Validity

- assesses the extent to which the test or measurement strategy measures a theoretical construct or trait

Main Approaches to Measurement and Data Collection in Research Methods

- Formal testing
- Interviewing
- Global ratings
- Observation
- Biological measures

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