The Two Independent Variables Are Speed of the Presentation (250

Multiple Choice

.The two independent variables are speed of the presentation (250 msec,1000 msec) and brightness of the background (dark,light) .Speed of presentation is a repeated measures variable,and brightness of the background is a random groups variable.Suppose the following mean were observed.What should the researcher conclude?

A) The two independent variables are not relevant variables in this experiment.
B) The main effect of the brightness variable is larger than the main effect of the speed of presentation variable.
C) The brightness variable should have been manipulated as a natural groups variable.
D) The interaction may be uninterpretable due to a possible floor effect.