If we have learned to solve problems by one method, we often have difficulty bringing new insight to similar problems. However, electrical stimulation of the brain appears to help subjects come up with fresh insight. In a recent experiment1 conducted at the University of Sydney in Australia, 40 participants were trained to solve problems in a certain way and then asked to solve an unfamiliar problem that required fresh insight. Half of the participants were randomly assigned to receive noninvasive electrical stimulation of the brain while the other half (control group) received sham stimulation as a placebo. The participants did not know in which group they were. In the control group, 20% of the participants successfully solved the problem while of the participants who received brain stimulation solved the problem.(A) Is this an experiment or an observational study?a. Experimentb. Observational study (B) From the description, does it appear that the study is double-blind, single-blind, or not blind?a. Double-blindb. Single-blindc. Not blind
(c) Make a two-way table of the data. Treatment Solved Not solvedShamElectrical
(d) What proportion of people who correctly solved the problem had the sham stimulation?Round your answer to two decimal places.
(e) Give values for, the proportion of people in the electrical stimulation group to solve the problem, and , the proportion of people in the sham simulation group to solve the problem. What is the difference in proportions ?Round your answer to two decimal places.