"Designing an Experiment Researchers want to know if there is a link between hypertension (high blood pressure) and consumption of salt. Past studies have indicated that the consumption of fruits and vegetables offsets the negative impact of salt consumption. It is also known that there is quite a bit of person-to-person variability in the ability of the body to process and eliminate salt. However, no method exists for identifying individuals who have a higher ability to process salt. The U.S. Department of Agriculture recommends that daily intake of salt should not exceed 2400 milligrams (mg). The researchers want to keep the design simple, so they choose to conduct their study using a completely randomized design.


Name three factors that have been identified."

Verified step by step guidance

1. Step 1: Understand what a 'factor' means in the context of an experiment. A factor is an independent variable that is controlled or observed to see its effect on the outcome. In this problem, factors are variables that might influence hypertension or the study results.
2. Step 2: Identify the first factor mentioned: 'consumption of salt.' This is a key variable because the researchers want to study its link to hypertension.
3. Step 3: Identify the second factor: 'consumption of fruits and vegetables.' Past studies suggest this affects how salt impacts blood pressure, so it is an important factor to consider.
4. Step 4: Identify the third factor: 'person-to-person variability in the ability to process and eliminate salt.' This biological variability can influence the outcome and is a factor even though it cannot be directly measured or controlled.
5. Step 5: Summarize the three factors as: (1) salt consumption, (2) fruit and vegetable consumption, and (3) individual differences in salt processing ability.

Key Concepts

Factors in Experimental Design

Factors are the independent variables or conditions that researchers manipulate or observe to determine their effect on the outcome. Identifying factors is crucial for structuring the experiment and analyzing how each influences the response variable.

Confounding Variables and Control

Confounding variables are external factors that may affect the outcome and obscure the relationship between the studied variables. Recognizing and controlling these variables, such as fruit and vegetable consumption, helps isolate the effect of the main factor—in this case, salt intake.

Randomization in Experimental Design

Randomization involves randomly assigning subjects to different treatment groups to reduce bias and evenly distribute unknown factors, such as individual variability in salt processing. This ensures that the results are more reliable and generalizable.