A practicing speech-language pathologist believes, from her clinical experience, that stuttering modification programs (ala Van Riper) have superior long-term effects than fluency shaping approaches. To scientifically test her impressions, sixteen adult male stutterers on her caseload are randomly assigned to one of two treatment conditions. Stuttering intervention continues for one year, after which time all sixteen subjects are dismissed from therapy. One full year after therapy has been discontinued, the clients are brought back to examine the residual effects of the stuttering therapy. A dysfluency count is taken from each subject during a 15 minutes of spontaneous conversation. The mean number of dysfluencies for the stuttering modification group is 34, while the mean for the fluency shaping group is 44. The pooled standard deviation was 20. a. Using only data from these 16 adults, what is the statistical power? b. How many more children must be added to each group to produce a power of .80