If a research article reports that "The mean performance scores
for the Normal Sleep, Reduced Sleep, and No Sleep groups were 18.0,
16.6, and 15.6, respectively, F (2, 36) = 2.95, p < .05," the
most accurate conclusion is that:
people who get no sleep perform significantly worse than people
who sleep a reduced amount.
people who get no sleep perform significantly better than people
who sleep a normal amount.
the three groups do not all come from populations with the same
mean, although it is not clear which population means are
different
conclusions about the relationship between amount of sleep and
performance cannot be drawn from these results