Spearman-Brown Prophecy Formula
The Spearman-Brown prophecy formula provides a rough estimate of how much the reliability of test scores would increase or decrease if the number of observations or items in a measurement instrument were increased or decreased. This formula is called the Spearman-Brown (S-B) formula because the idea was introduced by both C. Spearman and W. Brown in articles they wrote in 1910. This entry demonstrates two ways to calculate the S-B formula and show how the predictions in score reliability typically vary with increases or decreases in the numbers of items on a test.
The S-B formula is commonly used to estimate the full-test reliability from the half-test correlation when calculating split-half reliability. Split-half reliability is an internal-consistency strategy for estimating reliability that is similar to the ...
Looks like you do not have access to this content.
Reader's Guide
Assessment
Cognitive and Affective Variables
Data Visualization Methods
Disabilities and Disorders
Distributions
Educational Policies
Evaluation Concepts
Evaluation Designs
Human Development
Instrument Development
Organizations and Government Agencies
Professional Issues
Publishing
Qualitative Research
Research Concepts
Research Designs
Research Methods
Research Tools
Social and Ethical Issues
Social Network Analysis
Statistics
Teaching and Learning
Theories and Conceptual Frameworks
Threats to Research Validity
- All
- A
- B
- C
- D
- E
- F
- G
- H
- I
- J
- K
- L
- M
- N
- O
- P
- Q
- R
- S
- T
- U
- V
- W
- X
- Y
- Z