UMGC Independent Variable and Dependent Variable Definitions

Many important findings about nutrients have been made through scientific research. The scientific process involves making observations, developing hypotheses (predictions) about observations, testing hypotheses through experiments, evaluating results, and drawing conclusions based on evidence.

Cite all sources in a standard citation format (APA, MLA, other). Cited sources are worth 10 points.

Spelling, grammar, and punctuation are worth 5 points.

Answers must be in your own words.

(A) Define the terms below in your own words. (5 points)

1. Hypothesis
2. Independent variable and Dependent variable
3. Controlled (control) variable
4. Randomized trial
5. Double-blind study

(B) Short Answer. Answer the items below in your own words (20 pts)

1. Explain how the independent variable relates to the dependent variable in an experiment
2. Explain how a controlled (control) variable is different from an independent variable
3. Define correlation as it relates to an observation. Provide an example of data results where there is a correlation between the variables.
4. Define causality as it relates to experimental design and experimental results. Define in your own words and use the terms ‘independent variable’ and ‘dependent variable’ as part of your definition. Provide an example of data results where there is a causal relationship between the variables in an experiment.
5. True or False: A hypothesis statement does not need to mention the effect of the independent variable on the dependent variable. Explain the reasoning for your answer.

(C) For each of the three nutrition research scenarios below, provide the following information in your own words:

(i) State the purpose of the study

(ii) State the hypothesis. Explain what information you used to come up with a hypothesis statement.

(iii) State the variables in the scenario. What are the Independent, Dependent, and Controlled (control) variables?

(iv) Is this a double-blind study?

(v) Imagine that you conducted the experiment to test your hypothesis. Provide hypothetical results from the experiment (i.e., provide hypothetical data for the dependent variable). Do your hypothetical results support the hypothesis? Explain your answer.

SCENARIO 1: (20 pts)

A weightlifter reads about a new supplement that increases the size of muscles in less than one month. He wants to see if it actually works so he designs the following experiment with his friends. He divides them into two groups of 5. Before the experiment begins, he takes their weight and measures their major muscle groups. One group is given the supplement with water once a day after dinner for a month. The other group is given a placebo with water once a day after dinner for a month. Each group eats the same meals three times a day and works out the same way daily at the gym. The ages of the individuals vary from 20 – 50, and some are men and others are women. At the end of the month, the weightlifter takes the weight and measures the major muscle groups again of his friends.

(i) State the purpose of the study

(ii) State the hypothesis. Explain what information you used to come up with a hypothesis statement.

(iii) State the variables in the scenario. What are the Independent, Dependent, and Controlled (control) variables?

(iv) Is this a double-blind study? Explain your reasoning.

(v) Imagine that you conducted the experiment to test the hypothesis. Provide hypothetical results from the experiment (i.e., provide hypothetical data for the dependent variable). Do your hypothetical results support the hypothesis? Explain your answer.

SCENARIO 2: (20 pts)

During a school staff meeting, several staffers mentioned that it seemed to them that students who chose healthier food options at lunchtime missed fewer days from school during the school year. The high school dietitian and social worker decided to collect data to test the hypothesis. They received approval from the principal and superintendent to conduct their research study. The dietitian collected data about which students chose healthy food options at lunchtime. She collected data for one lunch period each day. The social worker independently checked the attendance records of the students who had lunch during that lunch period. At the end of the school year, they shared the data they collected over the school year then analyzed the results.

(i) State the purpose of the study

(ii) State the hypothesis. Explain what information you used to come up with a hypothesis statement.

(iii) State the variables in the scenario. What are the Independent, Dependent, and Controlled (control) variables?

(iv) Is this a double-blind study? Explain your reasoning.

(v) Imagine that you conducted the experiment to test the hypothesis. Provide hypothetical results from the experiment (i.e., provide hypothetical data for the dependent variable). Do your hypothetical results support the hypothesis? Explain your answer.

SCENARIO 3: (20 pts)

A nutrition researcher recently learned that several members of an ocean-side community have been complaining of headaches and nausea. The researcher met with members of the community to try to determine what they might all have in common. She learned that they all eat at Acme restaurant at least once per week. She approached the restaurant owner to discuss possible causes for the complaints. The owner and the chef are baffled, but then remembered that they started using a different brand of seafood seasoning. The nutritionist asks if she can conduct a research study, and the owner and chef agree. The researcher and her medical doctor colleague receive approval from their university to conduct the study. They pay 20 research participants (ages 20-21 years old, male and female) to participate in the study. Ten participants (five males, five females) are randomly assigned to one of two groups. One group will eat the dish prepared with the new brand of seasoning, and the other group will eat the dish prepared with the old, previously used brand of seasoning. Only the nutritionist and the chef are aware of which participant receives which seasoning. The medical doctor research partner will meet with each participant the day after they eat at Acme restaurant to conduct a health survey and assessment, including questions about headaches and nausea.

(i) State the purpose of the study

(ii) State the hypothesis. Explain what information you used to come up with a hypothesis statement.

(iii) State the variables in the scenario. What are the Independent, Dependent, and Controlled (control) variables?

(iv) Is this a double-blind study? Explain your reasoning.

(v) Imagine that you conducted the experiment to test the hypothesis. Provide hypothetical results from the experiment (i.e., provide hypothetical data for the dependent variable). Do your hypothetical results support the hypothesis? Explain