Question

eighteen individuals who use a particular form of social media were assigned a new user interface to use when logging in to their accounts. after using the new user interface for a week, each individual was asked to rate how easy or hard the new user interface was to use on a scale from 1 (extremely easy) to 9 (extremely hard). which of the following correctly identifies why this is not a well - designed experiment?
a there was a lack of control because not all individuals in the study used login passwords of the same length.
b the individuals may not have been randomly selected.
c there was not enough replication because the individuals used the new user interface for only one week.
d there was a lack of control because not all individuals in the study use social media.
e the study was not comparative—only one treatment was used.

Explanation:

A well - designed experiment typically has a control group for comparison. In this case, only one treatment (the new user interface) was used. Without a comparison (e.g., using the old interface as a control), it's difficult to draw valid conclusions about the new interface's ease of use.

• Option A: Password length is not relevant to the experiment about the user - interface's ease of use.
• Option B: Random selection is about sampling, not the experiment design's flaw in terms of comparison.
• Option C: One - week usage is a time - frame, not the main design flaw (lack of comparison).
• Option D: All individuals in the study use the particular social media (as per the problem statement).

Answer:

E. The study was not comparative—only one treatment was used.