Clue 1: Orient yourself
Which mark gives the best estimate?
Use the labels and the picture's left-to-right, near-to-far, or before-and-after order. Name only what you can point to.
The question
Which mark gives the best estimate?
Why it matters: Clinical recommendations affect real children and families. Fair comparisons, bias control, ethical limits, and honest uncertainty keep a promising result from becoming a harmful claim. Today you practice the professional reasoning behind that work: Effect size and confidence interval show magnitude and precision; a p-value measures model compatibility, not truth.
On your WebXam
Deciding significance from a confidence interval and p-value
For life
To find the cause, change one thing and watch what changes.
Principle: Same look, different cause
Five principles we return to
Having it is not using it
Same instructions, different switches
Same look, different cause
Change one thing and watch
Boss or doorman?
Decides the result or only allows it
Held down, not gone
Remove the brake and it returns
Many roads, one ending
One result can begin many ways
Try the everyday version first
A forecast needs an estimate and range, not a yes-or-no stamp
A forecast gives a best estimate plus a range of reasonable values. The range shows how much uncertainty remains around the center.
Do not jump to the biology yet. Treat the picture as a small system. Track its parts, follow one change at a time, and keep more than one explanation open until the picture supplies a way to separate them.
Clue 2: Trace one change
What does the width of the band show?
Follow one object, stage, or path. Point to the first place where the situation changes instead of jumping to the ending.
Clue 3: Keep the cause open
Why can a tiny gauge reading not prove the forecast is true?
List more than one explanation that still fits. Name the extra observation that would help you separate those possibilities.
Now inspect the illustration
Work from the visible evidence. A useful answer names the part of the picture that supports it and leaves unknown causes open.
- 1Which mark gives the best estimate?
- 2What does the width of the band show?
- 3Why can a tiny gauge reading not prove the forecast is true?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: Which mark gives the best estimate?
You can complete today's required check without opening the technical details below.
Ready for the real names? Optional tier 2
Technical rules and limits
Rule 1: Read the effect size first.
Rule 2: Use the interval to judge precision and compatible values.
Rule 3: Interpret the p-value with design, bias, and prior evidence.
Where the analogy stops: Statistical uncertainty is not weather uncertainty, and its meaning depends on model assumptions.
Carry the previous idea forward
Gene discovery combines broad scans, family structure, quality control, and independent replication.
Today's technical takeaway
Effect size and confidence interval show magnitude and precision; a p-value measures model compatibility, not truth.
Now map the same rules onto biology
Interpret two treatment estimates without a significance shortcut
Forecast estimate
Effect size
Forecast range
Confidence interval
Model gauge
P-value under a null model
Educational illustration, not a clinical photograph or a patient-specific study plan. Use the supplied evidence cards and claim ceiling.
Mateo's case file: evidence supplied in this lesson
EXP07-E1
Study A reports a risk ratio of 0.60 with a 95 percent interval from 0.37 to 0.98.
Why it matters: The estimate suggests lower risk, with values near no difference still close to the interval edge.
EXP07-E2
Study B reports a risk ratio of 0.55 with an interval from 0.18 to 1.67.
Why it matters: The result is much less precise and includes possible benefit, no difference, or harm.
EXP07-E3
A p-value is calculated under a statistical model and null hypothesis.
Why it matters: It is not the probability that the scientific claim is true or false.
Make the clinical decision
You are the data reviewer preparing a one-slide result summary.
A teammate wants to label Study A true and Study B false based only on whether p is below 0.05.
ACompare effect sizes, intervals, designs, and bias before stating the claim.
BUse p below 0.05 as proof and ignore magnitude.
CUse the larger-looking effect as proof even when its interval is wide.
Choose the interpretation and explain why the two intervals support different precision claims.
Evidence required
EXP07-E1 + EXP07-E2 Claim ceiling
You may describe magnitude, precision, and statistical compatibility. You may not convert a threshold into scientific truth.Go deeper Optional tier 3
Everything required for today is above. Open these only if you want the explainer, source trail, or download files.
The everyday model and Tier 1 check are the complete required path for this lesson.
Use these checks to keep your place. They are not turned in through the portal.
Check off as you finish
- Worked through the everyday picture and answered its three questions.
- Completed the Tier 1 check in plain words.
Turn in: Experimental Design lesson 7: Is the Association Real, or Just Chance?
Go to Schoology to turn this in.
Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Optional legacy technical materials Open only if you want the original notes, vocabulary, artifact, and CER work
Before this page, you should know
- A SNP is a single-letter spot where people commonly differ; a genome-wide association study (GWAS) tests hundreds of thousands to millions of SNPs at once without guessing a gene first.
- The (TDT) uses case-parent trios; a heterozygous parent should pass a 50 percent of the time by chance, so over- flags an associated .
If not, review
Today's new idea is only
An , a p-value, and a together decide whether an association is real, and the interval shows both the size and the certainty of the effect.
Goal: Students will interpret an , a p-value, and a , and decide whether an association is statistically significant.
Know by the end
- An association means two things tend to occur together; an (or ) measures effect size, where 1.0 means no difference.
- A p-value is the probability of a result at least this extreme if there were truly no effect; by convention p < 0.05 is called statistically significant.
- For a ratio measure, if the includes 1.0 the result is not significant; if it excludes 1.0 it is.
- TOPS reported a of 0.59 (95 percent CI 0.36 to 0.99, P = 0.04), so its result is significant but not by a wide margin; a CI that straddles 1.0 is a .
1
Three numbers
Model start: To judge an association we read three numbers: the (effect size, 1.0 means no difference), the p-value, and the .
- An association means two things tend to occur together; the (or ) measures effect size, and a value of ____ means no difference, above 1.0 raised risk, below 1.0 lowered risk.
- The p-value is the probability of a result at least this extreme if there were truly ____ (no) effect; by convention p < ____ (0.05) is called statistically significant.
2
Reading the interval
- The is the plausible range for the true effect; for a ratio, if the CI ____ (includes) 1.0 the result is not significant, and if it excludes 1.0 it is.
- The TOPS interval (0.36 to 0.99) just excludes 1.0, so the result is significant but not by a wide margin; a CI that straddles 1.0 is a .
3
Why pros prefer the interval
- The shows two things a bare p-value hides: the size of the effect and how precise it is.
- A small p-value makes pure chance an unconvincing explanation, but a wide interval that crosses 1.0 warns that the effect may be nothing at all.
Everything you need for today is on this page. These links are optional.
What to read
Read the short plain-language explanation written for this lesson. Plain-language explainer for this lesson
Why this source matters
This explanation gives you the background for today's idea without making you decode a research paper: An , a p-value, and a together decide whether an association is real, and the interval shows both the size and the certainty of the effect.
Words to unlock first
Reading moves
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Stop point
Stop after the final 'Use it now' section. The research citations are available separately for advanced readers.
Your output
Write one claim-evidence sentence: state the main idea, then name the example or evidence that supports it.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Experimental Design domain · Statistics for research, significance and confidence intervals
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Sort three practice findings into significant or not significant with one sentence each (Variant A: OR 2.1, 95 percent CI 1.3 to 3.4, p = 0.002; Variant B: OR 1.4, 95 percent CI 0.9 to 2.2, p = 0.11; Technique C: risk ratio 0.62, 95 percent CI 0.40 to 0.96, p = 0.03), then state whether the largest effect size is automatically the most trustworthy.
Lab / skill
Biomedical Innovations (BI) · Medical Interventions (MI)
Everything required for today's decision is already in the case file and plain-language explainer. The links below are original papers and database records for teachers and advanced readers, not assigned student reading.
- NEJM. Timing of Primary Surgery for Cleft Palate (TOPS), 2023.
- Gamble C, et al. 2023. Timing of Primary Surgery for Cleft Palate (TOPS trial). N Engl J Med. [PMID:37646677]
- Sabbagh HJ, et al. 2023. COVID-19 risk factors and orofacial clefts, five Arab countries: case-control study. BMC Oral Health. [PMID:37118740]
- Park JW, et al. 2007. Association between IRF6 and nonsyndromic cleft lip/palate in four populations. Genet Med. [PMID:17438386]
- Claim: The association reported in TOPS between earlier surgery and better speech is statistically significant.
- Evidence: The numbers were a of ____ with a 95 percent CI of ____ to ____ and P = ____.
- Reasoning: This counts as significant because the ____ (excludes 1.0) and the p-value ____ (is below 0.05).
How this is graded (rubric)
For: Sort three practice findings into significant or not significant with one sentence each (Variant A: OR 2.1, 95 percent CI 1.3 to 3.4, p = 0.002; Variant B: OR 1.4, 95 percent CI 0.9 to 2.2, p = 0.11; Technique C: risk ratio 0.62, 95 percent CI 0.40 to 0.96, p = 0.03), then state whether the largest effect size is automatically the most trustworthy.
| 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 through the route named under Submit here and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
How the model answer scores against this rubric
- CompleteProficient: Nothing is left blank: the model fills every part of "Sort three practice findings into significant or not significant with one sentence each (Variant A: OR 2.1, 95 percent CI 1.3 to 3.4, p = 0.002; Variant B: OR 1.4, 95 percent CI 0.9 to 2.2, p = 0.11; Technique C: risk ratio 0.62, 95 percent CI 0.40 to 0.96, p = 0.03), then state whether the largest effect size is automatically the most trustworthy.".
- 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 attached to your class form or handed in, and confirmed.
What's next: One p-value below 0.05 feels convincing, but a GWAS runs about a million tests at once. If 0.05 lets through a 1-in-20 fluke, how many flukes slip through a million tests, and why do gene studies demand a far tinier p-value?