A research study published in 2010 in the Archives of Neurology investigated the relationship between the results of a spinal fluid test and the presence of Alzheimer’s disease. The study included 114 patients with normal memories, 200 with memory problems, and 102 with Alzheimer’s disease. Each individual’s spinal fluid was analyzed to detect the presence of two types of proteins. Almost everyone with Alzheimer’s had the proteins in their spinal fluid. Nearly three quarters of the group with memory problems had the proteins, and each such member developed Alzheimer’s within five years. About one third of those with normal memories had the proteins, and the researchers suspect that those individuals will develop memory problems and eventually Alzheimer’s.
a. Identify the explanatory and response variable(s).
b. Was this an experimental or non-experimental study? Why?
c. Would it be possible to design this study as an experiment? Explain why or why not.