The endorphins released by the brain act as natural painkillers. For example, Gintzler (1980) monitored endorphin activity and pain thresholds in pregnant rats during the days before they gave birth. The data showed an increase in pain threshold as the pregnancy progressed. The change was gradual until 1 or 2 days before birth, at which point there was an abrupt increase in pain threshold. Apparently a natural painkilling mechanism was preparing the animals for the stress of giving birth. The following data represent painthreshold scores similar to the results obtained by Gintzler. Do these data indicate a significant change in pain threshold? Use a repeated measures ANOVA with α =.01.
Days Before Giving Birth  
Subject  7  5  3  1 
A  39  40  49  52 
B  38  39  44  55 
C  44  46  50  60 
D  40  42  46  56 
E.  34  33  41  52 
Given info:
Days before giving birth  
Subject  7  5  3  1  Total 
A  39  40  45  52 

B  38  39  44  55 

C  44  46  50  60 

D  40  42  46  56 

E  34  33  41  52 






Calculation:
Total:
And,
Within treatment:
And,
Between treatments:
For this example, we find
And,
Substitute for P, G, k and N,
Statistics for The Behavioral Sciences (MindTap Course List)
Essentials Of Statistics
Essentials of Statistics for The Behavioral Sciences (MindTap Course List)
Understanding Basic Statistics
Probability and Statistics for Engineering and the Sciences
Mathematical Excursions (MindTap Course List)
Elementary Technical Mathematics
Single Variable Calculus: Early Transcendentals
Mathematical Applications for the Management, Life, and Social Sciences
Single Variable Calculus
Precalculus: Mathematics for Calculus (Standalone Book)
Calculus (MindTap Course List)
Elements Of Modern Algebra
Applied Calculus for the Managerial, Life, and Social Sciences: A Brief Approach
Finite Mathematics and Applied Calculus (MindTap Course List)
Calculus of a Single Variable
Elementary Geometry For College Students, 7e
Calculus: Early Transcendental Functions (MindTap Course List)
Calculus: Early Transcendentals
Trigonometry (MindTap Course List)
Contemporary Mathematics for Business & Consumers
Calculus: Early Transcendental Functions
Finite Mathematics
Single Variable Calculus: Early Transcendentals, Volume I
Intermediate Algebra
Calculus: An Applied Approach (MindTap Course List)
Finite Mathematics for the Managerial, Life, and Social Sciences
Multivariable Calculus
Applied Calculus
Introduction To Statistics And Data Analysis
Study Guide for Stewart's Multivariable Calculus, 8th
Study Guide for Stewart's Single Variable Calculus: Early Transcendentals, 8th
Elementary Geometry for College Students