Question

does a platelet - rich plasma (prp) injection into the scalp promote hair growth? researchers identified 50 female patients with female pattern hair loss. the patients ranged in age from 30 to 60 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 patients hair density (number of hairs per square centimeter) and hair diameter (millimeters) was measured. the mean difference in hair density (pcp minus saline) was 64.41\\(\frac{hairs}{cm^{2}}\\) and the mean difference in hair thickness was 0.07 mm. complete parts (a) through (g) below. (e) who are the experimental units? a. females b. females with hair loss 30 to 60 years of age c. females 30 to 60 years of age d. the fifty female patients (f) what role does randomization play in this study? a. randomly select the female patients b. randomly choose which treatment to apply c. randomly choose the area of the scalp that receives the treatment. d. randomly select the type of patient

Explanation:

Step1: Understand experimental units

Experimental units are the entities on which an experiment is performed.

Step2: Analyze each option

• Option A: "Females" is too broad as the study is about female pattern hair - loss patients.
• Option B: "Females with hair loss 30 to 60 years of age" is still a general group, but the actual experimental units are the specific patients in the study.
• Option C: "Females 30 to 60 years of age" ignores the hair - loss condition.
• Option D: "The fifty female patients" are the specific entities on which the injections (PRP and saline) are applied.

Step1: Recall the role of randomization

Randomization in an experiment helps to reduce bias.

Step2: Analyze each option

• Option A: The patients are already identified (50 female patients with female pattern hair loss), not randomly selected.
• Option B: The treatments (PRP and saline) are not the focus of randomization in the context of the question.
• Option C: "A coin toss was used to decide which area received the PRP injection and which received a saline injection", which means randomization is used to choose the area of the scalp that receives the treatment.
• Option D: The type of patient (female with pattern hair loss) is already defined, not randomly selected.

Answer:

D. The fifty female patients