Observed systolic and diastolic paths with separate fitted slopesLive current inputs
Health & Fitness
Blood Pressure Trend Calculator
Fit separate least-squares trends through six period averages, quantify residual variation, and distinguish a directional signal from the latest reading.
Systolic slope—
Diastolic slope—
Latest period—
Endpoint change—
Systolic residual RMS—
Diastolic residual RMS—
Directional summary—
Interpretation guardrail—
LONGITUDINAL PRESSURE VIEW
Observed systolic and diastolic paths with separate fitted slopes
Observed pairs, fitted lines, and residual bands reveal whether an apparent change is broad or driven by one endpoint.
TREND LEDGER
Observed values and fitted residuals
Every period remains auditable against both fitted lines.
| Period | Systolic | Fitted systolic | Diastolic | Fitted diastolic | Category context |
|---|
TREND INPUT
Use comparable period averages
- Average readings taken with a consistent protocol.
- Keep the period length and time of day reasonably comparable.
- Enter six consecutive period averages.
- Record treatment or routine changes separately; the slope does not identify causes.
SIGNAL VERSUS NOISE
Direction and scatter answer different questions
The slope estimates broad direction. Residual RMS describes how tightly observations follow that line.
A favorable slope with wide scatter may still require better measurement consistency; a flat slope can coexist with clinically important high levels.
REGRESSION METHOD
Fit both pressures across the full observation window
Ordinary least squares estimates direction across all six period averages; it does not imply causation.
Detailed calculation process and general formulas
bS = Σ(ti-t_bar)(Si-S_bar) / Σ(ti-t_bar)^2bD = Σ(ti-t_bar)(Di-D_bar) / Σ(ti-t_bar)^2Annualized_S = bS × 52Residual_Si = Si - (aS + bS ti)RMS_S = sqrt(ΣResidual_Si^2 / n)Symbols, meanings, and units
- ti
- time of period iweeks
- Si
- period systolic averagemm Hg
- Di
- period diastolic averagemm Hg
- bS,bD
- fitted weekly slopesmm Hg/week
- RMS
- root-mean-square residual variationmm Hg
TREND DIAGNOSTICS
Do not compress the series into one arrow
The trend is split into three auditable layers.
Systolic direction
—A dedicated slope preserves the upper-pressure pattern.
Diastolic direction
—A separate slope avoids assuming both pressures move together.
Residual scatter
—RMS identifies departures from a smooth linear path.
Decision takeaway: Use the chart to prepare questions about measurement conditions and timeline events, not to infer why pressure changed.
Applied decisions
Patterns the dual trend can expose
Both pressures decline steadily
The fitted slopes are negative and residuals are small.
What the result clarifies: The evidence supports a directional summary across this entered window.
Systolic falls while diastolic is flat
The two slopes diverge.
What the result clarifies: A single combined trend label would lose material information.
Worked default scenario
Current-input substitution and reconciliation
Method references
Evidence used to frame this specific model
Scope and limitations
Historical trend analysis only. It does not diagnose, attribute treatment effect, or advise medication changes. Severe readings or concerning symptoms require appropriate medical assessment.
Blood Pressure Trend Calculator | Six-Period Systolic and Diastolic Slopes FAQ
Why use period averages?
They reduce the influence of one isolated reading, provided the measurement protocol is consistent.
Does a negative slope mean treatment worked?
No. The calculation shows association over time and does not identify causes.
Why report residual RMS?
It shows how much observations depart from the fitted line.
Can the latest reading replace the trend?
No. The latest observation and the multi-period direction answer different questions.