01 / A MODEL
Make the abstract visible.
A daily circle connects habit check-ins with a simplified estimate from population studies. The assumptions and uncertainty stay in view.
Explore the calculationA student biomedical engineering project
Small habits.
A bigger
picture.
Daily habits, real research, and one real measurement. Exploring what healthier living looks like when curiosity comes before certainty.
In developmentPhone-first. Research-led. v0.0.
THE EVERYDAY, EXAMINED.FIG. 01
A little more evidence.
YearExpander.CONCEPT
Your day, in perspective.Thursday, Oct 15
ILLUSTRATIVE ESTIMATE0.85h0.53–1.19 h model rangeof 24 h in a full circle
Estimate from population studies.
Not a prediction for you.
StrengthEvidence review next
Try the Move check-in. Nothing is saved.
ONE REAL MEASUREMENTYour camera. Your pulse.Illustrative waveform · feature planned
INTERACTIVE CONCEPT, NOT THE FINISHED APP01 / 03
Evidence before promises Personal records stay on your device Built to learn, in the open
01 / THE QUESTION
What if a habit
came with a footnote?
Longevity advice is everywhere.
The evidence is harder to see.
YearExpander is an attempt to make the connection visible: between what we do each day, what researchers have observed, and what a small piece of engineering can actually measure.
No miracle scores. No certainty where there isn’t any. Just a useful question, made tangible.
Here’s what’s being built02 / HOW IT WORKS
A model. A measurement.
A little more understanding.
Three connected ideas.
One phone-first web app.
02 / A MEASUREMENT
Find a pulse in the pixels.
The planned pulse feature uses a fingertip over the phone camera to explore PPG, filtering and signal quality. It will be tested against a reference device.
See the validation plan03 / THE EVIDENCE
Keep the source close.
Short, readable evidence cards explain the studies, their limits and the thinking behind the model. Every claim should have somewhere to lead.
Open the reading list03 / SHOW YOUR WORK
An estimate.
With the asterisk.
Start with a published association. Apply a simplified model. Make the assumptions visible. Then ask what the number can — and cannot — tell us.
The starting example is Wen et al. (2011): a cohort of 416,175 adults, where roughly 15 minutes of daily activity was associated with lower mortality. This was an observational study, not a trial proving extra time for an individual.
Wen et al. · The Lancet, 2011Population estimate, not a prediction for you.
A confidence interval does not capture all model uncertainty. Habit effects overlap and cannot be treated as independent gains.
EXPLORE THE ASSUMPTIONWorked example
The same study.
Two ways to estimate.
Change the assumed years of practice. The research stays the same; the displayed daily equivalent changes.
30 years70 years
Simplified Gompertz model0.85h / active day0.53–1.19 h from the HR interval
Using the study’s reported ~3 years1.44h / active dayPoint estimate; no matching range shown
What’s behind the calculation?
Study HR: 0.86 (95% CI 0.81–0.91). Assumed Gompertz slope b = 0.085 per year.
ΔLE ≈ −ln(HR) / b
hours per day = ΔLE × 24 / NThe HR interval is transformed in reverse order: HR 0.91 gives the lower estimate, HR 0.81 the upper. N is the assumed years of practice.
An educational approximation, not a validated life-expectancy calculator. The two methods disagree — that uncertainty is part of the project.
THE VALIDATION NOTEBOOKPLANNED STUDY
Illustrative Bland–Altman layout.
Real results will replace this graphic after testing.
04 / CHECK IT AGAINST REALITY
A measurement is only
as useful as its test.
The engineering question isn’t just “can a camera find a pulse?” It’s “how close does it get, and when does it fail?”
20+paired readings planned
2devices compared at once
The plan: compare the app with a pulse oximeter or smartwatch, report the mean error and MAE, and plot agreement. Movement, lighting and phone model belong in the results, too.
No results yet. The pulse feature is an educational measurement, not a diagnostic tool.
05 / THE ROAD AHEAD
Small steps.
Working versions.
Build it. Check it. Explain it.
Then take the next step.
v0.0WE ARE HERE
A home for the project
This landing page, a clear scope, and the first development note.
v0.1
Give the idea a working circle
Habit check-ins, a first evidence table, and transparent estimate calculations.
v0.2
Read the signal
Camera feasibility, a live PPG waveform, filtering and quality checks.
v0.3
Test the measurement
Paired readings, an honest error analysis, and a validation report.
v1.0
Bring the pieces together
Workout logging, the exercise library, evidence cards and offline use. Food logging comes last.
06 / BEHIND THE PROJECT
Learning by
building something real.
An independent student project exploring biomedical engineering, one testable idea at a time.
YearExpander brings together research, mathematical modelling and biosignal processing. The aim is to understand each step well enough to explain it — including its limitations.
AI helps with writing and checking code. Reading the studies, collecting measurements and drawing conclusions remain the author’s work.
Student project · Biomedical engineering07 / FIELD NOTES
The work behind
the work.
A dated record of what takes shape,
what needs fixing, and what comes next.
ENTRY 001 / v0.0
FIRST STEPS
A home for an idea.
YearExpander starts with a page, a research question and a deliberately small first step. This version introduces the concept and an interactive example of the estimate model.
Read the project note
What’s here
A responsive landing page, clearly labelled screen concepts, a worked example based on Wen et al., and a roadmap for the app.
The question to keep open
Turning a population association into a daily number requires assumptions. The two calculation methods do not agree, so both are shown. Neither is a personal forecast.
Next up
Read and document the habit studies, verify the calculations, and check camera and torch support on the target phones before building the pulse feature.
This note documents the project state. The author’s personal learning diary and validation results are still to come.
Next note: the first working habit circle.
THE READING LIST
Follow the footnotes.
A starting point for the project’s literature review.
More curiosity.
Fewer promises.