Description
Return max(0,enteredAt-windowStart) and max(0,windowEnd-max(windowStart,enteredAt)).
Epidemiological windows encode observation and classification rules on a timeline. Endpoint inclusion, late entry and supplied washout periods change counts, but a local timing flag does not establish infection, clinical risk or a validated case definition.
Return max(0,enteredAt-windowStart) and max(0,windowEnd-max(windowStart,enteredAt)).
When to use this tool
Use Risk Window Left Entry Offset when you need a supplied surveillance-time or risk-window calculation.
How to use the tool and how it works
- Enter windowStart, enteredAt, windowEnd. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read entryOffset, observedDuration. Use the output convention below.
Require ordered risk-window endpoints. Return max(0,enteredAt-windowStart) and max(0,windowEnd-max(windowStart,enteredAt)).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| windowStart | Window Start | Required. Finite number. |
| enteredAt | Entered At | Required. Finite number. |
| windowEnd | Window End | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| entryOffset | Entry Offset | Required. Finite number. |
| observedDuration | Observed Duration | Required. Finite number. |
{
"input": {
"windowStart": 10,
"enteredAt": 15,
"windowEnd": 30
},
"output": {
"entryOffset": 5,
"observedDuration": 15
}
}Limitations and assumptions
- Entry offset is not capped at window length and entry after the window gives zero observed duration. No exit, censoring, event risk or actual eligibility is inferred.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Apply the appropriate study protocol or public-health definition to verified records. Resolve calendar, clock, follow-up and censoring conventions before interpreting timing as epidemiological evidence.
References
Similar or alternative tools
- Risk Window Halfopen Boundary
Test event at or after start and strictly before end, and flag exact equality with the excluded end.
- Exposure Window Left Truncation Days Tool
Split a supplied half-open exposure window at observation entry without inferring exposure or incidence.