Question

Consider an experiment to investigate the effectiveness of different insecticides in controlling pests and their impact on the productivity of tomato plants.

What is the best reason for randomly assigning treatment levels (spraying or not spraying) to the experimental units (farms)?

A)Random assignment eliminates the effects of other variables, like soil fertility.
B)Random assignment allows researchers to generalize conclusions about the effectiveness of the insecticides to all farms.
C)Random assignment eliminates chance variation in the responses.
D)Random assignment helps avoid bias due to the placebo effect
E)Random assignment will tend to average out all other uncontrolled factors such as soil fertility so that they are not confounded with the treatment effects.

Answer 1

Randomly assigning treatment levels ensures that uncontrolled factors such as soil fertility do not confound treatment effects, allowing for a clear cause-and-effect connection to be established between explanatory and response variables in an experiment. Therefore correct option is E

Step-by-step explanation:

The best reason for randomly assigning treatment levels to experimental units in an experiment is E) Random assignment will tend to average out all other uncontrolled factors such as soil fertility so that they are not confounded with the treatment effects. By randomly assigning treatments, any potential lurking variables are spread equally among the groups. This ensures that the only difference between groups is the one imposed by the researcher. As a consequence, different outcomes measured in the response variable must be a direct result of the different treatments, allowing the experiment to demonstrate a cause-and-effect connection between the explanatory and response variables.