Question 3 : Suppose you believe that a specific type of plant will grow better in soil than in sand. You want to run an experiment to test your hypothesis.

Question

Describe an experiment you could run to investigate whether a specific type of plant grows better in soil than in sand.

What are the treatments in your experiment?
The treatment would be the soil or sand the plants grow in.

What is the response variable in your experiment?

The response variable in my experiment is the amount of plant growth

Where in your experiment would random selection occur?
Random selection occurs when the plants are chosen (from the location you are getting your plants from).

Where in your experiment would random assignment occur?
Random assignment occurs when the plants are assigned to solid or sand.

Answer 1

Your experiment to test whether a specific type of plant grows better in soil than in sand is well-conceived. Below, I provide a detailed outline of the experiment, emphasizing the treatments, response variable, random selection, and random assignment.

Experiment Design

Objective: To investigate whether a specific type of plant grows better in soil than in sand.

Treatments

The treatments in your experiment are:

1. Soil Treatment: Plants grown in soil.
2. Sand Treatment: Plants grown in sand.

Response Variable

The response variable in your experiment is the amount of plant growth, which can be measured in several ways such as:

• Height of the plants (in centimeters or inches).
• Biomass (dry weight or fresh weight of the plants).
• Number of leaves or branches as indicators of overall health and growth.

Random Selection

Random selection occurs during the process of choosing the plants for the experiment. You would randomly select plants from a larger population of the specific type you are testing (e.g., through random sampling methods such as drawing lots or using a random number generator to select them from a larger batch).

Random Assignment

Once you have randomly selected the plants, random assignment occurs when you allocate the selected plants into the two treatment groups (soil or sand). This could be done using random methods, such as tossing a coin, drawing from a hat, or using a random number generator to ensure that each plant has an equal chance of being placed in either of the treatment groups.

Additional Considerations

1. Control Variables: To ensure a fair test, keep other factors constant such as light, water, temperature, pot size, and number of plants per treatment.
2. Replicates: Use multiple plants in each treatment group to increase the reliability of your results (e.g., at least 10 plants in each treatment).
3. Duration of Experiment: Decide on a specific time frame for measuring growth (e.g., 4 weeks, 8 weeks).
4. Measurement: Plan how and when you will measure the growth (e.g., weekly measurements of height, final biomass measurement at the end of the experiment).
5. Data Analysis: Determine how you will analyze the data collected (e.g., using statistical tests like t-tests to compare the means of the two groups).

By following this structured approach, you can effectively test your hypothesis about the growth of the specific type of plant in different types of substrates (soil vs. sand).