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Bradford Absence Index from Spells & Days

Calculate the arithmetic Bradford index from absence spells and total absent days, with neutral numerical bands and explicit limits.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Results are estimates for planning and education. Confirm rates, taxes, fees, and legal requirements with the relevant institution or a qualified professional before making a financial decision.

Formula and method

Three absence spells totaling ten days give an index of 90: 3 × 3 × 10. One ten-day spell gives 10, illustrating the formula’s greater weight on frequency.

Bradford index = absence spells² × total absent days

Worked example

Enter these known values and leave the other values blank.

Number of separate absence spells
3
Total absent days in the chosen period
10
Arithmetic Bradford index
90

Assumptions and limitations

  • Use one consistent observation period, up to 366 days in this model. The number of spells is a nonnegative whole number; fractional days can represent partial-day absence.
  • Zero spells and zero days give a zero index. A nonzero number of spells requires a positive total duration, and vice versa.
  • The formula deliberately squares the spell count. It does not measure an individual’s health, motivation, performance or reasons for absence.
  • Numerical bands are retained only to describe the calculated index. They must not automatically trigger warnings, discipline or dismissal. Review circumstances, applicable policy and any required adjustments separately.
  • Inverse results are meaningful only for feasible inputs. When the index and days are both zero, the spell count cannot be uniquely inferred from the formula alone.

Common questions

Does a high score justify an employment decision?

No. It is a numerical summary of frequency and duration. The result does not explain the absences or determine an appropriate employment action.

References

Bookify permits up to 366 absent days for leap-year periods, requires whole spell counts and rejects inconsistent zero-spell or zero-day combinations.

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