Mini Preregistration Reflection (Biology Edition)
Welcome! This one‑page guide walks you through a tiny, classroom‑friendly preregistration. Think of it as a planning snapshot: what you’ll test, how you’ll test it, and how you’ll avoid overclaiming. Short, sweet, and science‑savvy.
1) Mini‑Preregistration Outline
Pick a very small, doable biology question. Here’s a concrete example to model your own.
Example Question
Do bean plants watered with a dilute sugar solution grow taller over 10 days than bean plants watered with plain water?
Variables
- Independent variable: Type of water (plain water vs. 1% sugar solution)
- Dependent variable: Plant height (cm) on Day 10
- Controlled variables: Same seed type, same soil, same pot size, equal light, same room, same watering volume and schedule
Hypotheses
- H0 (null): Mean height is the same for sugar and water groups.
- H1 (alternative): Mean height differs between groups (two‑sided) — or specify one‑sided if you predict a direction.
Prediction (Directional, if appropriate)
If sugar provides an accessible energy source or affects osmotic balance beneficially at low concentration, plants in 1% sugar will be taller on average than those with plain water.
Controls
- Negative/control group: Plain water
- Procedural controls: Same planting day, randomized pot positions, identical care routine
Analysis Sketch
- Summary: Compute mean and standard deviation of height per group.
- Visualization: Side‑by‑side dot plot or box plot of heights.
- Statistical test: Two‑sample t‑test (equal/unequal variance as checked) or Mann–Whitney U if non‑normal/small N.
- Assumptions to check: Independence (separate pots), approximate normality, similar variance; note any violations.
- Effect size: Mean difference and 95% CI.
Tip: Keep N small and manageable (e.g., 6–10 plants per group) so it’s classroom‑friendly.
2) One‑Sentence “Update” for Two Possible Outcomes
Write a one‑sentence update that cleanly states what changed in your beliefs or plan after seeing data — no drama, just clarity.
- Outcome A (Sugar > Water): “Our data show taller plants with 1% sugar (mean difference = X cm, 95% CI [L, U]); this supports our directional prediction, so we’ll next test 0.5% vs 1% to probe dose response.”
- Outcome B (No Difference): “Heights did not differ meaningfully between groups (mean difference ≈ 0, 95% CI includes 0); we update toward ‘no practical effect’ at 1% and will explore different concentrations or longer growth time.”
Keep it one sentence, include the effect size/CI if you can, and state your next step.
3) Overclaiming Checklist (Scope • Assumptions • Limitations)
Use this quick scan before sharing conclusions.
Scope
- Am I only claiming effects for the specific species, conditions, and time frame I tested?
- Did I avoid generalizing to different concentrations, species, or environments I didn’t measure?
Assumptions
- Independence: Were pots truly separate and handled similarly?
- Measurement: Was height measured the same way each time (same tool, same person, same time of day)?
- Model fit: Do my test’s assumptions (normality/variance) look reasonable or documented if violated?
Limitations
- Sample size: Is my N small, and do I say that limits precision?
- Variability: Do I report uncertainty (CI/error bars) rather than only a p‑value?
- Practical vs. statistical: If significant, is the effect large enough to matter? If not significant, do I avoid saying “no effect” and instead say “no detectable effect under these conditions”?
- Reproducibility: Did I record enough detail for someone to repeat this?
Pro tip: If a claim isn’t supported by the design or data, rephrase it as a question or future direction.
Exit Ticket (Reflect Briefly)
- One misconception I corrected today:
e.g., “I thought any p < 0.05 means the effect is big; now I know p‑values don’t measure effect size.”
- One question I still have:
e.g., “How do I choose between a t‑test and a non‑parametric test with very small samples?”
You just built a mini roadmap for honest, crisp science. Keep it tiny, keep it tidy, and let your data do the talking!