Experimental vs observational
Thu, Mar 4, 2027 · Week 7 · Biotechnology for Health (Biomedical Innovations)
Today's goal: Distinguish experimental from observational studies and choose the right design and sample size.
What a finished product looks like
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
Study design decision (pre-lab)
My physiology question: Does 2 minutes of step-ups raise heart rate compared to rest?
Classification: experimental. Justification: I actively manipulate the independent variable (I assign the exercise condition) rather than just watching what people happen to do, which is what makes a study experimental.
Three examples I classified:
- Comparing heart rate before and after an exercise I assign: experimental (I manipulate exercise).
- Recording resting heart rates of students and noting their reported sleep: observational (nothing is manipulated).
- Giving half the group caffeine and half none, then measuring heart rate: experimental (I assign the condition).
Sample-size estimate: at least 15 participants, each measured at rest and after exercise.
Rationale: a larger sample reduces the chance that one unusual person skews the result and makes the average more reliable, while 15 is realistic for one class period.
Also due today: Submit your design choice and sample-size rationale to the Schoology pre-lab assignment today.
WebXam problem for today's skill
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.