Lisa is working on a science project: Her task is to answer the question: “Does Rogaine (which is a commercial hair product) affect the speed of hair growth?” Her family is willing to volunteer for the experiment. Describe how Lisa would perform this experiment. In your answer, clearly identify the experimental and response variables and design your experiment to include a positive control and a negative control. (There is more space on the back of this page to continue your answer)
The Correct Answer and Explanation is:
To perform this experiment, Lisa needs to carefully design a scientific investigation that allows her to test whether Rogaine affects the speed of hair growth. She will need to identify the experimental variable, the response variable, and include both a positive control and a negative control group to ensure valid and reliable results.
1. Experimental Variable:
The experimental variable is the use of Rogaine. This is the factor Lisa will change between the groups.
2. Response Variable:
The response variable is the speed of hair growth, which can be measured in millimeters or centimeters over a set period of time.
3. Experimental Design:
Lisa will need several family members to participate and will divide them into three groups:
- Experimental Group (Rogaine Group): These individuals will apply Rogaine to a specific area (such as a patch on the scalp) once a day, following the product’s instructions.
- Positive Control Group (Alternative Growth Product): This group will use another hair growth product that is already known to stimulate hair growth. This helps confirm that the experiment can detect a real effect when one exists.
- Negative Control Group (Placebo): These individuals will apply a non-active substance (like water or a neutral moisturizer with no hair growth ingredients) to the same area. This ensures that any observed changes are due to Rogaine and not from rubbing or moisture alone.
4. Measurement and Duration:
Lisa will measure hair length at the start and then at regular intervals (e.g., weekly) for at least 4 to 6 weeks. She must ensure that all groups are similar in age, health, and hair type to minimize other variables.
5. Data Analysis:
At the end of the experiment, she will compare the average hair growth between the three groups. If the Rogaine group shows significantly more growth than the negative control, this suggests Rogaine is effective.
This design uses proper scientific controls and allows Lisa to draw meaningful conclusions from her data.
