Ed is doing a survey of popular colors for cars for a school report. he decides to take a sample by sitting near a busy intersection and nothing the colors of the cars as they go by him. ed counts 23 black cars, 9 red cars, 17 blue cars, 25 white cars and 21 silver cars during 20 minutes of watching. how many more white and blue cars are there than silver and red cars

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