L-J chart is used for monitoring -a)  Accuracyb)  Precisionc)  Sensitivityd)  Specificity
The formulation of Westgard rules were based on statistical methods. 
Westgard rules are commonly used to analyse data in Shewhart control Charts Westgard rules are used to define specific performance limits for a particular assay and can beused to detect both random and systematic errors.
ac
ab
ad
bc