Geology Fission Track Central Age Calculator
Explicit zero-overdispersion fixed-effects fission-track central log-age estimate with independent grain variances; not pooled track-count age or estimated random-effects dispersion. Caller independently establishes matching units, evidence, method edition and applicability; output is not compliance, diagnosis, work-safety approval, geological identity or validated hazard prediction.
Description
Combining log ages with inverse-variance weights gives a fixed-effects mean on the log scale.
Combining log ages with inverse-variance weights gives a fixed-effects mean on the log scale.1
Its exponent is a weighted geometric age, and this implementation does not estimate the extra dispersion of a full central-age model. Use this tool to calculate fission track central age from the supplied measurements and assumptions.
When to use Geology Fission Track Central Age Calculator
Use this tool to calculate fission track central age from the supplied measurements and assumptions. Establish the measurement units, sampled interval, calibration or model edition and geological assumptions before entering data.
How to use Geology Fission Track Central Age Calculator and understand its results
- Establish the measurement units, sampled interval, calibration or model edition and geological assumptions before entering data.
- Enter grainLogAges, independentLogAgeVariances, using the field meanings and rules below, then run the tool.
- Read fixedEffectsGeometricCentralAge, logAgeStandardError. Interpret the fields using their units, signs and evidence conventions below.
- If input validation fails, correct the reported field and run again. Before applying the result, check reference scope, model assumptions and any missing evidence or placeholder values.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| grainLogAges | Grain log ages | list of number | Required |
| independentLogAgeVariances | Independent log age variances | list of number | Required |
Enter nonempty aligned finite natural-log grain ages and positive independent log-age variances. Weight each log age by inverse variance, compute the weighted log mean, exponentiate it and return sqrt(1/totalWeight) as its log-scale standard error. No excess-dispersion or random-effects parameter is fitted; the returned standard error is not an age-scale error.
age=exp(Σ(logAge_i/variance_i)/Σ(1/variance_i)); logStandardError=√[1/Σ(1/variance_i)] Use the exact units, boundary rules, ordering and missing-evidence conventions above.
| Output field | Meaning | Value type |
|---|---|---|
| fixedEffectsGeometricCentralAge | Fixed Effects Geometric Central Age; follow the units, sign, ordering and evidence convention stated above | number |
| logAgeStandardError | Standard error on the natural-log age scale, not the age scale | number |
{
"input": {
"grainLogAges": [
0,
1.3862943611198906
],
"independentLogAgeVariances": [
1,
1
]
},
"output": {
"fixedEffectsGeometricCentralAge": 2,
"logAgeStandardError": 0.7071067811865476
}
}Limitations and assumptions
Its exponent is a weighted geometric age, and this implementation does not estimate the extra dispersion of a full central-age model. Interpretation depends on the units, sampling scope and exact model described above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse evidence arrays fail validation; the specific bounds and alignment requirements are stated above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful result reporting false, no matches or missing evidence.
Alternative or Complementary methods
Use Geology U Th Disequilibrium Age Calculator for this related task: An activity-ratio age interpretation depends on a specified uranium–thorium evolution curve.
Use Geology U Pb Discordia Upper Intercept Calculator when its separate inputs and assumptions fit the question: A discordia line summarizes paired uranium–lead ratio observations in a chosen coordinate system.
References
Similar or alternative tools
- Geology U Th Disequilibrium Age Calculator
An activity-ratio age interpretation depends on a specified uranium–thorium evolution curve.
- Geology U Pb Discordia Upper Intercept Calculator
A discordia line summarizes paired uranium–lead ratio observations in a chosen coordinate system.