Loss Development Factors (LDFs) and Tail Factors

This dataset provides detailed loss development factors, including age-to-age, cumulative, and tail factors by insurance line of business and development period. It enables actuaries and analysts to project ultimate losses, assess reserve adequacy, and benchmark against industry standards, supporting robust financial and risk management decisions.

  • last updated 2 Nov 2025
  • by GoMask
The brief that made it

Projecting ultimate insurance losses for financial reporting and reserving

Sample rows

preview · 8 of 400 rows · all 10 columns
ldf_idintegerfactor_sourcestringdevelopment_period_endintegerline_of_businessstringdevelopment_period_startintegerage_to_age_factorfloatcumulative_development_factorfloattail_factorfloateffective_datedatenotesstring
1Internal Study12Auto01.871.87blank2022-09-15Initial auto claims, rapid early development observed.
2Industry Benchmark12Property01.951.95blank2022-10-01Large property losses, catastrophe event start period.
3External Peer Group12Liability12.012.01blank2022-10-25Boundary: Large commercial liability start.
4Consultant Analysis24Health121.111.44blank2022-11-10Major medical, large claims development in year two.
5Industry Benchmark24Auto121.081.52blank2022-12-02Includes both personal and fleet auto policies.
6Internal Study24Property121.091.49blank2022-12-15Property claims, moderate development after first year.
7Consultant Analysis24Liability121.131.54blank2023-01-05Liability claims, ongoing litigation effects.
8External Peer Group36Health241.071.66blank2023-01-30Outlier: epidemic scenario, high volatility.

What the 400 rows show

from the 400-row sample

Actuarial Judgment (factor source) stands out: mean development_period_end is 50.1, against 33.8 for the rest.

  • 36median development_period_end
  • 24median development_period_start
  • 1.1median age_to_age_factor
  • 1.6median cumulative_development_factor
  • 1.1median tail_factor
Mean development_period_end by factor_source400 rows
0408033.7Indust…125 rows40.0Consul…91 rows29.0Intern…74 rows30.5Extern…59 rows50.1Actuar…51 rows
development_period_end400 rows, in bands of 10
0459018785781721281104080development_period_end →

Median 36, from 6 to 72.

line_of_business400 rows · 4 values
  1. Property104
  2. Auto102
  3. Liability98
  4. Health96
10 columns by typefrom the column list below
  • string 3
  • integer 3
  • float 3
  • date 1

Columns

10 columns in three groups
blueprint · 10 columns
columntypedescriptionexample
Text 3 columns
line_of_businessstringInsurance line of business (e.g., Auto, Property, Liability) for which the development factors applyAuto
factor_sourcestringSource or method used to derive the development factors (e.g., industry benchmark, internal study)5 sources · optionalInternal Study
notesstringAdditional notes or comments regarding the factor set or its applicationoptionalInitial auto claims, rapi…
Numbers 6 columns
ldf_idintegerUnique identifier for each loss development factor recordunique · 1 or more1
development_period_startintegerStarting age or period (in months or years) for the age-to-age development factor0 or more0
development_period_endintegerEnding age or period (in months or years) for the age-to-age development factor0 or more12
age_to_age_factorfloatAge-to-age development factor for projecting losses from one period to the next0 or more1.87
cumulative_development_factorfloatCumulative development factor from origin to the current development period0 or more1.87
tail_factorfloatTail factor applied beyond the last observed development period to estimate ultimate losses0 or more · optional1.01
Dates and times 1 column
effective_datedateDate when the development factors become effective or were last updatedoptional2022-09-15

Use it for

  • median develop…36400 rowsmean development peri…33.7Indu…40.0Cons…29.0Inte…30.5Exte…

    An insurance dashboard

    Development_period_end by factor_source and a breakdown of line_of_business. Excel, Power BI or Tableau.

  • Why do the 51 Actuarial Judgment rows have a mean development_period_end of 50.1?

    A root-cause class exercise

    Hand out the rows and one question. The answer is in the data, not in the brief.

  • A software demo

    Believable rows with line_of_business, development_period_start and development_period_end to fill a screen in front of a buyer.

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This dataset400 rows10 columns
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blueprint · loss-development-factors-ldfs-and-tail-factors

Behind this dataset

Same schema. As many rows as you need.

These 400 rows came out of a blueprint — 10 columns with generation rules behind each one. Open it in Data Factory to retune a column, add your own, wire in foreign keys, and run it at the size you actually need.

Rules it was built with
  • Age-to-age factor = Loss at age N+1 / Loss at age N
  • Average or weighted average of age-to-age factors
  • Selection of development factors based on credibility
  • Volume-weighted vs simple average methods
  • Cumulative LDF (CDF) to ultimate
  • Tail factor for development beyond triangle
  • Industry benchmarks for tail (e.g., workers comp 1.02-1.10)
  • Shorter tail for property (tail near 1.00)
Rows
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Exports
CSV, JSON, JSONL, Parquet, SQL, Excel, TSV, XML
Licence
yours to use, including commercially
API slug
loss-development-factors-ldfs-and-tail-factors

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