U statistics 

U test 

UBCR estimator 

UBDP test 

ultimate cluster 

ultrametric inequality 

UMP test 

unadjusted moment 

unbiased confidence intervals 

unbiased critical region 

unbiased error 

unbiased estimating equation 

unbiased estimator 

unbiased sample 

unbiased test 

underdispersion 

unequal subclasses 

uniform distribution 

uniform sampling fraction 

uniform scores test 

uniform spectrum 

uniformity trial 

uniformly best constant risk estimator 

uniformly best distance power test 

uniformly better decision function 

uniformly minimum risk 

uniformly most accurate 

uniformly most powerful test 

uniformly unbiased estimator 

unimodal 

unionintersection principle 

unionintersection tests 

unique factor 

uniqueness 

unit Normal variate 

unit stage sampling 

unitary sampling 

unitemporal model 

univariate distribution 

universe 

unlikelihood ratio 

unreduced designs 

unreliability 

unrestricted random sample 

unweighted mean 

unweighted means method (in variance analysis) 

up and down method 

up cross 

upper control limit 

upper quartile 

upward bias 

Ushaped distribution 

Uspensky's inequality 

Utest 

utility theory 
