Observer 2    
  + -    
+ 14 8 22 73.33%
- 6 2 8 26.67%
  20 10 30  
  Actual agreement= 53.33%  
  Chance agreement= 57.78%  
  Kappa statistic= -0.11  
Table 1: Correlation between positive IgA and severe ITP (PLT count <80000).