A researcher is examining the claims made by a water softener salt manufacturer. He performs an experiment using water from a va
riety of sources. For each water source, he has a sample with no treatment and a sample treated with the recommended amount of the water softener salt. He then tests each sample to measure the softness and compares the results, determining that the claims made by the manufacturer are true.
The conclusion drawn from the study is ___ because the sample is __ In this instance, an __ study was performed.
