An investigator wanted to see whether packaging information affects the way teenagers rate the effectiveness of soap. The same soap was put in three packages: (a) a pink wrapper that says "For Keeping Your Skin Baby Soft"; (b) a red wrapper that says "For Eliminating Acne"; and (c) a white wrapper that says nothing. Each teenager was asked to rub his or her face with dirt and wash with soap A; the same procedure was followed for soaps B and then C. The time it took to get the face clean was recorded each time. What is the intended independent variable?A) SoapB) Soap effectivenessC) Packaging informationD) The identity of the teenager

According to the federal regulations, which of the following studies meets the definition of research with human subjects? a study of twenty 4th grade classrooms in which researchers ask the schools to systematically vary the time of day reading is taught, and collect weekly assessments of reading comprehension for each child over a three-month period.the collection of data, by a playground designer hired by the superintendent of schools, about the physical dimensions of school playgrounds, presence of fencing, and the kinds of equipment currently provided.a feasibility study for implementing a year-round school program, focusing on economic issues such a facilities utilization and transportation costs.an analysis of aggregate data comparing statewide high school graduation rates provided by the state department of public instruction, using county tax information.