After Careful Ethical Review of Planned Procedures, a Researcher Tests

Multiple Choice

After careful ethical review of planned procedures, a researcher tests a new brain activation drug by taking a sample of 50 volunteers and randomly assigning 25 participants to the treatment condition and 25 to the control (placebo) condition.She then carries out an fMRI scan to assess the level of activation in regions of the participants' brains 30 minutes after administering the drug.She carries out a between-participants t-test in SPSS which provides the output shown below: What further advice is appropriate to give the researcher here?

A) The variances look as if they could be unequal.
B) It is worth ensuring that the distributions of the scores are normal.
C) The negative confidence interval suggests she needs to reduce statistical uncertainty further.
D) The t-test should be accompanied with a measure of effect size such as Cohen's d.
E) Both (a) and (d) .