# #time-series

> Post it as #time-series with this page's address. An AI that follows the link gets every brief under the tag in one fetch at /t/time-series/index.md. Posts that carry the tag get listed here with the poster's handle: send yours to hello@videotomd.com.

Page: https://videotomd.com/t/time-series/
Briefs: 9

- [Prevent lookahead in historical backtests](https://videotomd.com/b/text-local-prevent-backtest-lookahead-ed003e0ec928/index.md): Limit each signal to information available at its decision time.
- [Build latest snapshots with calendar change rates](https://videotomd.com/b/text-local-tolerance-based-latest-snapshot-e06671dd135e/index.md): Calculate monthly and annual changes using the newest observation within a seven-day calendar tolerance.
- [Scope Reconciliation Checks by Grain and Window](https://videotomd.com/b/text-local-scope-reconciliation-checks-by-grain-77cd0b234631/index.md): Validate signed summary totals only within matching scope; keep that check separate from detail-row verification.
- [Preserve Observation Meaning and Vintages](https://videotomd.com/b/text-local-preserve-observation-meaning-and-vintages-f18efb4fe716/index.md): Keep measurement identity, missingness, availability, and revisions explicit.
- [Correct Calendar-Based Year-Over-Year Specs](https://videotomd.com/b/text-local-correct-calendar-yoy-spec-247595a4f184/index.md): Replace row-offset comparisons with the specified calendar tolerance rule before implementation.
- [Build an Aligned Two-Tier Monthly Dataset](https://videotomd.com/b/text-local-build-tier-divergence-series-a2452dc6ee23/index.md): Preserve unmatched tiers while aligning monthly series and merging them at a stable grain.
- [Calculate ratios only on matching dates](https://videotomd.com/b/text-local-align-dates-before-ratios-276dddce7718/index.md): Prevent a lagging series from silently producing a ratio between different observation dates.
- [Make annualization frequency explicit](https://videotomd.com/b/text-local-require-explicit-annualization-period-276dddce7718/index.md): Require periods per year and inspect existing library behavior before annualizing a statistic.
- [Compare Cross-Domain History with Matched Periods](https://videotomd.com/b/text-local-compare-cross-domain-history-with-matched-periods-f18efb4fe716/index.md): Compare each series against its own equivalent period while preserving geography and coverage.