case0202 {Sleuth3}

Anatomical Abnormalities Associated with Schizophrenia

Description

Are any physiological indicators associated with schizophrenia? In a 1990 article, researchers reported the results of a study that controlled for genetic and socioeconomic differences by examining 15 pairs of monozygotic twins, where one of the twins was schizophrenic and the other was not. The researchers used magnetic resonance imaging to measure the volumes (in cm^3) of several regions and subregions of the twins' brains.

Usage

case0202

Format

A data frame with 15 observations on the following 2 variables.

Unaffected

volume of left hippocampus of unaffected twin (in cm^3)

Affected

volume of left hippocampus of affected twin (in cm^3)

Source

Ramsey, F.L. and Schafer, D.W. (2013). The Statistical Sleuth: A Course in Methods of Data Analysis (3rd ed), Cengage Learning.

References

Suddath, R.L., Christison, G.W., Torrey, E.F., Casanova, M.F. and Weinberger, D.R. (1990). Anatomical Abnormalities in the Brains of Monozygotic Twins Discordant for Schizophrenia, New England Journal of Medicine 322(12): 789–794.

Examples

attach(case0202) 
str(case0202)  

diff <- Unaffected-Affected    
summary(diff)
t.test(diff) # Paired t-test is a one-sample t-test on differences 
t.test(Unaffected,Affected,pair=TRUE)  # Alternative coding for the same test 

boxplot(diff,       
  ylab="Difference in Hippocampus Volume (cubic cm)", 
  xlab="15 Sets of Twins, One Affected with Schizophrenia", 
  main="Hippocampus Difference: Unaffected Twin Minus Affected Twin") 
abline(h=0,lty=2)   # Draw a dashed (lty=2) horizontal line at 0    
  
## BOXPLOT FOR PRESENTATION:
boxplot(diff, 
  ylab="Difference in Hippocampus Volume (cubic cm)", 
  xlab="15 Sets of Twins, One Affected with Schizophrenia",
  main="Hippocampus Difference: Unaffected Minus Affected Twin",  
  col="green", boxlwd=2, medlwd=2, whisklty=1, whisklwd=2, 
  staplewex=.2, staplelwd=2, outlwd=2, outpch=21, outbg="green",
  outcex=1.5)      
abline(h=0,lty=2) 

detach(case0202)