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

Random assignment eliminates the effects of other variables, like soil fertility, and allows researchers to draw accurate conclusions about the effectiveness of the insecticides. So the correct answer is option A.

Step-by-step explanation:

The best reason for randomly assigning treatment levels to the experimental units in this experiment is that random assignment eliminates the effects of other variables, like soil fertility (option A).

Random assignment ensures that the treatment groups are comparable, with similar distributions of lurking variables. This allows researchers to isolate the effects of the insecticides and draw accurate conclusions about their effectiveness on controlling pests and impacting tomato plant productivity.

For example, if farms were not randomly assigned to treatment levels, there could be inherent differences in soil fertility between the groups. This could confound the results, making it difficult to determine if any observed differences are due to the insecticides or the soil fertility.