Critique the following statement:
When there are no significant differences between the experimental and control groups, we can safely conclude that the independent variable does not have an effect.
When there is no difference between the experimental and control groups, this is termed a null effect. It is difficult to interpret the cause and we cannot safely include that the independent variable does not have an effect.
The reason may be due to:
1. IV having no effect
2. IV not adequately manipulated
3. Problem with the DV (ex: floor or ceiling effects)
4. Insufficient control of extraneous (control) variables