Question

researchers are investigating the effect of ph level in water on the breeding habits of the moon jellyfish. as part of a laboratory experiment, they will randomly assign one of three treatments, low ph, medium ph, or high ph, to the water in the tanks that hold the jellyfish. which of the following is the best reason for the random assignment of a treatment level to an experimental unit? a randomization tends to minimize the effects of uncontrolled variables, such as water temperature, so that such factors are not confounded with the treatment effects. b randomization will make up for improper experimental design, data collection, and analysis. c randomization makes the analysis easier since the data can be entered into the computer in any order. d randomization is required by statistical consultants before they will analyze the experiment. e randomization means that the experiment would not need to be replicated.

Explanation:

Random assignment in an experiment helps to balance out the effects of uncontrolled variables. By randomly assigning treatments (like different pH levels here), other variables (such as water temperature) are more likely to be evenly distributed across the treatment groups. This prevents these uncontrolled variables from being confounded (mixed up) with the treatment effects. Option B is incorrect because randomization cannot fix improper experimental design. Option C is wrong as the ease of data entry is not the main reason for randomization. Option D is not a valid scientific reason - it's about the scientific purpose, not what statisticians require. Option E is incorrect because replication (repeating the experiment) is still important in experiments even with randomization.

Answer:

A. Randomization tends to minimize the effects of uncontrolled variables, such as water temperature, so that such factors are not confounded with the treatment effects.