API ReferenceQuant Signals
CPCV validation
/api/v3/validation/cpcv- Plan
- Starter and up
- Price
- 3 credits per call
- MCP tool
cpcv
Subsample Sharpe dispersion over the combinatorial group splits of CPCV (AFML Ch. 12) on a return series you POST: the series is cut into n_groups time blocks and the Sharpe of every k-block subset is reported (n_splits = C(n_groups, k); n_paths = AFML's backtest-path count, k/n_groups x C(n_groups, k)). Nothing is refit, so it is NOT an out-of-sample test and cannot detect overfitting or selection bias: a series picked as the best of many backtests scores about its in-sample Sharpe here too. Call it when the user asks how stable a return series' Sharpe is across time; to ask whether a Sharpe is real or a multiple-testing artifact, use deflated_sharpe with the number of trials.
Request body
application/json, required.
returnsarray of numberRequiredFlat per-period return series.
n_groupsintegerOptional10embargo_daysintegerOptional5kintegerOptional2annualisationnumberOptional252Response
A 200 is a JSON envelope: ok: true and this endpoint's own fields (see Quant Signals). It carries X-Request-ID, the credit headers (X-Credits-Cost, X-Credits-Remaining, X-Credits-Receipt, X-Credits-Settlement) and the rate-limit headers.
A 200 is billed even when it holds no data (an empty list, null, found: false), so check those fields. Pricing & credits explains the credit headers.
Errors
No error is billed. The body is { "ok": false, "error", "detail", "request_; read the code from error.
| Error | Meaning |
|---|---|
400 invalid_ticker | The request is malformed, for example a ticker that is not a symbol: invalid_ticker, refused before any credit is reserved, with param naming the parameter. Not billed. |
401 unauthorized | Missing or invalid API key. |
402 plan_required | Your plan does not include this tool, you are out of credits, or your workspace's spend cap paused its keys. plan_required names the plan that unlocks the tool; usage_exceeded means the credit balance is spent; spend_cap_reached means the key is paused until the cap resets or is raised: detail names the cap and the reset, cap_usd and resets_at (ISO 8601) carry them, and doc_url links pricing and credits. Not billed. |
403 scope_denied | This API key is limited to some products and this tool is not one of them. product names the tool's product and scopes the key's products. An upgrade does not change it: use a key whose scopes include the product, or change this key's scopes. Not billed. |
404 not_found | No such resource. Not billed. |
422 validation | A parameter is missing, out of range or the wrong type; param names it. Not billed. |
429 rate_limited | Your plan's rate limit is spent for this window. Retry after Retry-After seconds. Not billed. |
503 paid_ | The data could not be served completely right now; retry later. Not billed. |
504 request_timeout | The request ran past the server's time budget; retry. Not billed. |
This table lists what the spec declares for this route. Error responses lists every code FIRM sends, with when to retry.
Guides
Read the Quant Signals guide for this endpoint's fields and examples.