Overview
This lecture discusses the key components of experiments, focusing on treatment and control groups, controlled experiments, and the characteristics of a "good" experiment in scientific research.
Treatment and Outcome Variables
- The treatment variable represents what the subject receives (e.g., a drug in a study).
- The outcome variable measures the result of interest (e.g., memory test results in Alzheimer patients).
- Subjects are divided based on whether they received the treatment ("yes") or not ("no").
Treatment and Control Groups
- The treatment group consists of subjects who receive the item of interest (e.g., the new drug).
- The control group consists of those who do not receive the treatment.
Controlled Experiments
- A controlled experiment is defined by researchers assigning subjects to groups and dictating what they receive.
- The keyword indicating a controlled experiment is "given" (subjects given either drug or placebo).
Gold Standards of Good Experiments
- A large sample size increases the likelihood that the group represents the overall population.
- Random assignment minimizes bias by ensuring all types of people are in both treatment and control groups.
- Using a placebo allows for blind or double-blind studies, reducing expectation effects.
- In a blind study, subjects don't know if they received treatment; in a double-blind study, neither subjects nor researchers know.
- Double-blinding is often achieved using a third party to administer treatment and collect data.
Practical Takeaways
- Large, random samples are always important and feasible for making a good experiment.
- Placebos and blinding are ideal but not always possible.
Key Terms & Definitions
- Treatment Variable — what the subject receives in an experiment (e.g., drug or no drug).
- Outcome Variable — the measured result or effect of the treatment (e.g., test score).
- Treatment Group — subjects who receive the treatment.
- Control Group — subjects who do not receive the treatment.
- Controlled Experiment — experiment where researchers assign treatments to subjects.
- Placebo — an inactive substance given to control group.
- Blind Study — subjects do not know if they’re receiving treatment or placebo.
- Double-Blind Study — both subjects and researchers do not know which group receives the treatment.
- Random Assignment — randomly allocating subjects to groups to minimize bias.
Action Items / Next Steps
- Review the definitions of treatment, control, placebo, and random assignment.
- Prepare for further discussion of large and random samples in phase two of statistics.