Question

Corn variety 1 yielded 140 bushels per acre last year at a research farm. This year, corn variety 2, planted in the same location, yielded only 110 bushels per acre. Unfortunately, we don’t know whether the difference is due to the superiority of variety 1 or to the effect of this year’s drought. This is an example of

(a) bias due to voluntary response.

(b) confounding.

(c) lack of blinding.

(d) sampling variability.

(e) the placebo effect.

Short answer

The answer is option (b) confounding.

Step-by-step solution

Given Information

Corn variety 1 yielded 140 bushels per acre last year. And, corn variety 2, planted in the same location, yielded only 110 bushels per acre.

Explanation

Since we don't know whether the difference in bushels per year is due to the superiority of variety 1 or the effect of a year's drought.

Two variables are confounded when their effects on a response variable cannot be distinguished from each other. In this case, we cannot differentiate between the effect of the variables of variety and weather, which implies that this is an example of confounding.