Question

select the correct answer from each drop-down menu.

a researcher is examining the claims made by a water softener salt manufacturer. he performs an experiment using water from a variety 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 valid/invalid because the sample is unbiased/biased. in this instance, an observational/experimental study was performed.

Explanation:

Identify the study type

The researcher actively applies a treatment (water softener salt) to one sample and compares it to an untreated control sample from the same source. This active manipulation of an independent variable defines an experimental study rather than an observational study.

Evaluate the sampling and validity

The researcher uses water from a variety of sources and tests both treated and untreated samples for each source. This broad, paired sampling process avoids selection bias, making the sample unbiased and the resulting conclusion valid.

Answer:

The conclusion drawn from the study is <blank>valid</blank> because the sample is <blank>unbiased</blank>. In this instance, an <blank>experimental</blank> study was performed.