x => r2017.11.06-select-zipfian-latency.log 
y => 9acbd68815499fc7f8fbb5931d643b8fd7804a80-select-zipfian-latency.log 

          n min    max median   average     stddev  p99
x 239462176 0.5 240.20    0.5 0.5174487 0.18355276 1.05
y 239462176 0.5   1.05    0.5 0.5123944 0.08162911 1.05

.3                 0.4                 0.5                0.6                   
+|------------------+-------------------+------------------+-------------------|
                                        +                                       
1                                       |                                       
                                        +                                       
                                        +                                       
2                                       |                                       
                                        +                                       
Legend: 1=data$x, 2=data$y

At 95% probablitiy:
===> average is statistically significant     (p=0.000000, diff ~0.005054)
===> variance is statistically significant    (p=0.000000)