Just When You Can’t Read One More Thing, from Kim Zussman

2011-05-01 · Kim Zussman
Original source

Here are the mean monthly returns for gold ETF "GLD", 2002-present, by two groups: months Nov-Apr, and months May-Oct (vs zero):

One-Sample T: nov-apr, may-oct

Test of mu = 0 vs not = 0

Variable    N     Mean   StDev   SE Mean       95% CI            T      P
nov-apr     41  0.02504  0.05267  0.0082  ( 0.0084, 0.0416) 3.05 0.004
may-oct   36  0.00851  0.05303  0.0088  (-0.0094, 0.0264)  0.96  0.342

Both positive, but only the mean for months nov-apr is significantly different from zero (and 3x greater than may-oct)