A potential difficulty with experiments such as test markets is that outside factors, such as the actions of competitors, can distort the results by affecting , such as sales.

dependent variable.

Explanation: A potential difficulty with experiments such as test markets is that outside factors, such as the actions of competitors, can distort the results by affecting dependent variable such as sales. A variable whose value depends on that of another is called dependent variable. Furthermore, A dependent variable is the variable being tested and measured in a scientific experiment, it is something that depends on other factor.

i’m   sure probably just geuss and see which one you can get right, i’m pretty sure it is the combination of goods and services