Description
Return unobservedDays = max(0, min(windowEnd, observationEntry)-windowStart) and observedDays = max(0, windowEnd-max(windowStart, observationEntry)).
Epidemiological timing depends on which event defines the origin, how intervals include their boundaries and whether time is observed. Numeric day coordinates and elapsed intervals do not by themselves select a calendar or a transmission model.
Return unobservedDays = max(0, min(windowEnd, observationEntry)-windowStart) and observedDays = max(0, windowEnd-max(windowStart, observationEntry)).
When to use this tool
Use Exposure Window Left Truncation Days when reconciling supplied day coordinates, observation windows or interval boundaries.
How to use the tool and how it works
- Enter windowStart, windowEnd, observationEntry. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read unobservedDays, observedDays. Use the output convention below.
Require windowStart <= windowEnd. Return unobservedDays = max(0, min(windowEnd, observationEntry)-windowStart) and observedDays = max(0, windowEnd-max(windowStart, observationEntry)). Use common numeric day coordinates; durations use elapsed boundaries without adding an inclusive day.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| windowStart | Window Start | Required. Safe integer. |
| windowEnd | Window End | Required. Safe integer. |
| observationEntry | Observation Entry | Required. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| unobservedDays | Unobserved Days | Required. Safe integer. |
| observedDays | Observed Days | Required. Safe integer. |
{
"input": {
"windowStart": 0,
"windowEnd": 100,
"observationEntry": 30
},
"output": {
"unobservedDays": 30,
"observedDays": 70
}
}Limitations and assumptions
- Entry before the window leaves it fully observed, and entry after the window leaves it fully unobserved. The tool does not detect right censoring, missing visits, intermittent exposure or actual observation quality.
- 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
Use an explicit calendar conversion for real dates and a suitable transmission or censoring model for inference beyond these local time calculations.
References
Similar or alternative tools
- Contact Risk Window Overlap Duration Term
Return overlap = max(0,min(contactEnd,riskEnd)-max(contactStart,riskStart)); overlaps is true only when the untruncated difference is strictly positive.
- Risk Window Left Entry Offset Tool
Locate supplied left entry on a half-open risk window without imputing events.