1. Intro to Stats and Collecting Data
Intro to Stats
1:52 minutesProblem 1.3.19a
Textbook Question
A company wants to test the effectiveness of a new acne cream. The company recruits 500 girls ages 13 to 17 who have acne. The subjects are randomly assigned into two groups. One group is given the acne cream and the other is given a placebo that looks exactly like the acne cream. Both groups apply the cream daily for two months. Facial photos are taken at the beginning and end of the treatment to compare results.
Identify the experimental units and treatments used in this experiment.
Verified step by step guidance1
Step 1: Define the experimental units. Experimental units are the individuals or objects on which the experiment is conducted. In this case, the experimental units are the 500 girls aged 13 to 17 who have acne.
Step 2: Identify the treatments. Treatments refer to the conditions applied to the experimental units. Here, the treatments are the acne cream and the placebo cream.
Step 3: Explain the random assignment. The subjects are randomly assigned into two groups to ensure that any differences observed are due to the treatments and not other factors. Random assignment helps eliminate bias and confounding variables.
Step 4: Describe the measurement process. Facial photos are taken at the beginning and end of the treatment period to compare the effectiveness of the acne cream versus the placebo. This provides a quantitative or qualitative basis for evaluating the results.
Step 5: Highlight the purpose of the placebo. The placebo is used to control for psychological effects, such as the placebo effect, where subjects might perceive improvement simply because they believe they are receiving treatment. This ensures the results are attributable to the acne cream itself.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Video duration:
1mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Experimental Units
Experimental units are the smallest division of experimental material to which a treatment is applied. In this study, the experimental units are the 500 girls aged 13 to 17 who have acne. Each girl represents an individual unit that receives either the acne cream or the placebo, allowing researchers to assess the treatment's effectiveness.
Recommended video:
5:37
Introduction to Probability
Treatments
Treatments refer to the specific conditions or interventions applied to the experimental units in an experiment. In this case, there are two treatments: one group receives the actual acne cream, while the other group receives a placebo that mimics the cream's appearance. This design helps isolate the effect of the acne cream by comparing it against a control group.
Random Assignment
Random assignment is a technique used to ensure that each experimental unit has an equal chance of being assigned to any treatment group. This method helps eliminate bias and confounding variables, making the results more reliable. In this experiment, the random assignment of the girls into the two groups (acne cream and placebo) enhances the validity of the findings regarding the cream's effectiveness.
Recommended video:
Guided course
07:09Intro to Random Variables & Probability Distributions
2:13mWatch next
Master Introduction to Statistics Channel with a bite sized video explanation from Patrick
Start learning
