Buying a New Phone: Experimental design

Laurel is wondering if it would be more realistic to test phone durability through a bending test rather than a crushing test. To find out, she convinces four of her friends to join her at an electronics store and bend one of the two phones for a duration of 1 minute each.

Two of her friends really want to try to bend the Universe S10, so Laurel assigns those two friends to bend the Universe S10, and her other two friends try bending the WePhone 10S.

The Universe S10 was bent about 2 degrees more than the WePhone 10, so Laurel concludes that the average treatment effect of the WePhone 10S on bendability is -2 degrees. Of the following, which is the most problematic design error in this experiment?

Possible Answers

Noncompliance
Ethics
Random assignment
Not enough data

Exercise

Buying a New Phone: Experimental design

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