A researcher wishes to examine the effects of a new medical treatment on patients with Alzheimer's disease. The researcher plans to examine the effects on a group of randomly selected subjects. What is wrong with this design? Select all that apply. A. A control group is not used. B. Only one researcher is used. C. Subjects are not randomly assigned to an experimental group and control group. D. An entire population is not used.

Aresearch study is studying the effects of a new drug for osteoporosis alzheimer's disease (ad) for women above the age of 65 years. a group of individuals with osteoporosis is randomized into two groups. one group is treated conventionally, and the second group is treated with the new medication. assessments are made at 3, 6, 12, 36, and 48 months. the conventionally treated group is assessed for ad using a serum blood test, and the treatment group is assessed for ad using a pet radiotracer that binds to beta-amyloid plaques. in comparing these 2 trial arms, the authors of the study may encounter which type of bias? a. selection bias on the risk of developing b. measurement bias c. confounding bias d. recall bias e. lead-time bias