Survivors-only average vs whole-cohort average, by starting year
Answered against 22 years of US equities and 12 years of US options data and published with the query that produced it. This result is stored as of 2026-09-20, from Survivorship Bias in Stock Data, Explained.
| cohort_year | cohort_size | gone_count | survivors_only_pct | full_universe_pct | gap_pct |
|---|---|---|---|---|---|
| 2016 | 2728 | 974 | 196.7 | 140 | 56.7 |
| 2017 | 2522 | 823 | 151.5 | 111.1 | 40.4 |
| 2018 | 2669 | 829 | 112.8 | 82.6 | 30.1 |
| 2019 | 2646 | 701 | 130.6 | 107 | 23.5 |
| 2020 | 2669 | 645 | 81.7 | 69.1 | 12.6 |
| 2021 | 3416 | 965 | 59.1 | 44.5 | 14.6 |
| 2022 | 3378 | 703 | 29.6 | 21.3 | 8.3 |
- Rows × columns
- 7 × 6
- Computed
- Completeness
- No missing values
- Source
- US exchange, SIP and OPRA market data
- Licence
- Strasmore terms · free, no signup
What each column holds
| Column | Type | Range | Notes |
|---|---|---|---|
cohort_year |
text | 7 distinct values (2016, 2017, 2018…) | |
cohort_size |
number | 2,522 to 3,416 | |
gone_count |
number | 645 to 974 | count |
survivors_only_pct |
number | 29.6 to 196.7 | percent |
full_universe_pct |
number | 21.3 to 140 | percent |
gap_pct |
number | 8.3 to 56.7 | percent |
Computed from Strasmore's warehouse of US exchange, SIP and OPRA market data. Equity prices are delayed; options greeks and implied volatility are end-of-day. This result is stored, not recomputed on load — it is exactly the numbers that were returned on , and the query below is what returned them.
Run it yourself
This is the exact query behind the result above. Change a ticker, a date or a column and run it against the warehouse — no account, no key. The no-signup tier is smaller than the one this page was computed on; a query that reaches past it comes back saying which plan runs it.
WITH
entry AS
(
SELECT
ticker,
toYear(date) AS cohort_start,
argMin(toFloat64(close), date) AS entry_close
FROM global_markets.stocks_daily_aggs
WHERE toMonth(date) = 1
AND date BETWEEN '2016-01-01' AND '2022-01-31'
AND ticker NOT IN ('SPCX')
GROUP BY ticker, cohort_start
HAVING argMin(toFloat64(close), date) >= 5
AND avg(volume) >= 250000
),
outcome AS
(
SELECT
ticker,
argMax(toFloat64(close), date) AS final_close,
max(date) AS last_bar
FROM global_markets.stocks_daily_aggs
WHERE date >= '2016-01-01'
GROUP BY ticker
)
SELECT
toString(e.cohort_start) AS cohort_year,
count() AS cohort_size,
countIf(o.last_bar < today() - 45) AS gone_count,
round(100 * avgIf(o.final_close / e.entry_close - 1, o.last_bar >= today() - 45), 1) AS survivors_only_pct,
round(100 * avg(o.final_close / e.entry_close - 1), 1) AS full_universe_pct,
round(100 * (avgIf(o.final_close / e.entry_close - 1, o.last_bar >= today() - 45)
- avg(o.final_close / e.entry_close - 1)), 1) AS gap_pct
FROM entry AS e
INNER JOIN outcome AS o ON o.ticker = e.ticker
GROUP BY e.cohort_start
HAVING countIf(o.last_bar >= today() - 45) > 0
ORDER BY e.cohort_start
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