Dr Patton correctly suggests that psychological intervention should
be assessed in the evidence based arena. It is important that the
impressive results of Guthrie's study be replicated in other locations,
but "bigger" samples of patients are not mandatory. Statistical tests are
designed to take sample size into account. A statistical difference is a
statistical difference whatever the sample size. Large samples are more
likely to help find out clinically subtle but statistically robust
differences.
Rapid Response:
Other samples needed, but why bigger ?
Dr Patton correctly suggests that psychological intervention should
be assessed in the evidence based arena. It is important that the
impressive results of Guthrie's study be replicated in other locations,
but "bigger" samples of patients are not mandatory. Statistical tests are
designed to take sample size into account. A statistical difference is a
statistical difference whatever the sample size. Large samples are more
likely to help find out clinically subtle but statistically robust
differences.
Competing interests: No competing interests