When Is a Mouse a Good Stand-In for Mateo?
Experimental Design domain · Lesson 11 of 20 · Biomedical Innovations (BI)
Today's goal: Judge a proposed mouse study by face validity and construct validity, and apply the 3Rs (Replacement, Reduction, Refinement) and ARRIVE reporting to decide whether the model can honestly answer a human question.
What a finished product looks like
This is a model of the work you should turn in. Use it to check your own: match the structure and the level of detail, do not copy it. Your wording should be your own.
1. Validity: The design aims at both validities, but only earns construct validity if the knocked-out gene truly sits in the human cleft pathway, and only earns face validity if the pups are actually born with a visible cleft. Right now I have neither result, only a plan.
2. The 3Rs: This ignores Reduction. The number 200 has no power justification; it was picked, not calculated. Fix: run a power calculation before ordering animals so we use the fewest that still give a valid answer.
3. Mateo link: If 20% of the mice cleft, I could claim the gene contributes to clefting in this model with partial penetrance. I could not claim it causes Mateo's cleft, because a model is evidence, not proof, and the human leap is its own limitation.
How this was built, step by step
The finished product above did not appear all at once. Here is the path from the question to the turned-in work, so you can follow the same steps.
- 1Start from today's question: When does studying a mouse actually teach us something true about Mateo, and when does it fool us?
- 2Work the Model and the Explore questions to reason it out before writing anything.
- 3Pull the specific evidence the product needs from the reading and any database you used.
- 4Write it up in the required format: A junior researcher proposes: knock out a human -pathway gene in 200 mice and see if they cleft. As PI, write three short notes back: (1) Validity: does this aim for , , or both, and what is your evidence? (2) : name one R this proposal ignores and how to fix it (hint: where did 200 come from?). (3) Mateo link: if 20% of these mice cleft, what could you and could you not claim about a real human like Mateo?
- 5Check it against the rubric, then submit.
| Criterion | Proficient | Developing | Beginning |
|---|---|---|---|
| Complete | Every required part of the artifact is present and filled in. | Most parts are present, but one is missing or left blank. | Several parts are missing. |
| Accurate | The science and data are correct and match the evidence. | Mostly correct, with a small factual slip. | Key science or data is wrong. |
| Scientific reasoning (CER) | States a claim, backs it with specific evidence, and explains the reasoning. | Has a claim and evidence, but the reasoning is thin or missing. | Gives an answer with no evidence or reasoning. |
| Professional communication | Clear, organized, and labeled the way a clinician or scientist would write it. | Readable but disorganized or missing labels. | Hard to follow. |
| Submitted | Turned in the right way (Schoology for routine work) and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
- CompleteProficient: Nothing is left blank: the model fills every part of "A junior researcher proposes: knock out a human cleft-pathway gene in 200 mice and see if they cleft. As PI, write three short notes back: (1) Validity: does this aim for construct validity, face validity, or both, and what is your evidence? (2) The 3Rs: name one R this proposal ignores and how to fix it (hint: where did 200 come from?). (3) Mateo link: if 20% of these mice cleft, what could you and could you not claim about a real human like Mateo?".
- AccurateProficient: Every number and claim matches the case evidence.
- Scientific reasoning (CER)Proficient: It names a claim, cites the specific evidence, and explains the reasoning, not just the answer.
- Professional communicationProficient: It is organized and labeled like a real chart note.
- SubmittedProficient: It would be turned in on Schoology and confirmed.
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.