Does a platelet-rich plasma (PRP) injection into the scalp promote hair growth? Researchers identified 30 female patients with female pattern hair loss. The patients ranged in age from 20 to 45 years. For each patient, two areas with hair loss were identified. A coin toss was used to decide which area received the PRP injection and which received a saline injection. Injections were given to each patient at one-week intervals. After 6 months the change in the patient's hair density (number of hairs per square centimeter) and hair diameter (millimeters) was measured. The mean difference in hair density (PCP minus saline) was 59.47 hairs>cm2 and the mean difference in hair thickness was 0.08 mm.

(a) What type of experimental design is this?
(b) What is the population that is being studied?
(c) What are the response variables in this study?
(d) What is the treatment?
(e) Who are the experimental units?
(f) What role does randomization play in this study?
(g) Draw a diagram similar to Figure 7 or 8 to illustrate the design.

                                                                               

                                                           

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Figure 7 Random assignment of plants to treatments Group 1 receives 20 plants Group 2 receives 20 plants Group 3 receives 20 plants Treatment A: No fertilizer Treatment B: 2 teaspoons Treatment C: 4 teaspoons Compare yield