Data Sources
The public sources behind reference figures in Caspenda guides — NYU Stern, BLS, Vanguard, Bengen, Trinity Study, Morningstar, Freddie Mac and more.
Caspenda’s calculators do not pull live market data — every assumption is yours to change. But when our guides reference real-world figures (long-run returns, inflation, fee averages, withdrawal research, retirement benchmarks), those figures come from the public sources below.
| Source | What we use it for |
|---|---|
| NYU Stern — Aswath Damodaran | Long-run U.S. equity returns (about 10% nominal / ~7% real since 1926) |
| U.S. Bureau of Labor Statistics | CPI-U inflation history and purchasing-power figures |
| Vanguard (2012) | DCA vs lump-sum investing research |
| William Bengen (1994) & Trinity Study (1998) | Safe-withdrawal-rate research behind the 4% rule |
| Morningstar & Investment Company Institute | Average fund fees and fee-trend data |
| Global X — QYLD | Covered-call ETF distributions, fund characteristics and official total-return history |
| Invesco — QQQ | Official QQQ fund performance and long-term growth figures |
| Cboe Global Indices | Nasdaq-100 buy-write / covered-call index methodology |
| SEC Investor.gov | Plain-English investing definitions, including total return |
| Freddie Mac — PMMS | Reference mortgage rates |
| Federal Reserve — Survey of Consumer Finances | Observed household retirement-account ownership and balance data |
| Social Security Administration | Retirement benefit eligibility, claiming-age and benefit context |
| IRS | Retirement-account contribution, catch-up, withdrawal and required-minimum-distribution rules |
| Medicare.gov / CMS | Medicare eligibility and enrollment context used in early-retirement planning |
Each source links to the relevant page wherever a figure is used. Where a claim cannot be verified against a source like these, we leave it out rather than approximate it.
Caspenda is not affiliated with any of these organizations. Their data is used for educational reference only.
Want the formulas instead? See the Methodology — and how we test our calculators.
Last updated: September 2026.