
between the groups are big relative to the error within groups, then we
can say with some known confidence that the independent variable
causes a change in the dependent variable.
One-Way Analysis of Variance
The t-test can be adapted to a single-group design, where the question is
whether the group mean equals some given value, usually zero; in this
case, there are n − 1 degrees of freedom in the denominator. If we have
more than two groups, it may seem tempting to perform pairwise t-tests
between all the different conditions to see if any of them differ sig-
nificantly from any of the others. This is clearly not okay, as it allows the
analyst to capitalize ...