Selected research example
Gage Park canceled graffiti requests: a status-cohort caution
All categories · Status: Canceled
12-month frequency comparison
- October 2024–September 2025
- 265
- October 2025–September 2026
- 7
- Change in monthly mean
- -21.5
The two windows each contain 12 complete covered months. The magnitude of the change is 37.86-fold. These are published requests, not a population-adjusted rate. Fixed windows do not establish a breakpoint, remove all seasonal effects or prove a renewal explanation.
How to read this example
This example compares 265 and 7 graffiti requests carrying the Canceled status at retrieval. The decline is large enough to pass the frequency screen, but the selected status creates an important interpretation problem: it is today’s saved classification applied to requests grouped by their creation month.
The comparison does not tell us that incoming graffiti reports fell by the same amount, that fewer incidents occurred, or that removal improved. Workflow changes, cancellations and the time available for a request to move between statuses can change the membership of historical cohorts. The chart has not reconstructed a month-by-month status history.
The first useful challenge is to inspect all graffiti requests without a status restriction over the same dates. Comparing status shares and checking the publisher’s definitions could then help distinguish a volume pattern from an administrative one. Those checks have not been completed here. The example is published to make the limitation visible, not to turn an administrative flag into a neighborhood outcome.
Saved observations and fitted phases
Phase suggestions withheld: serial pattern remains in the candidate fits. Manual boundaries can explore, not confirm, a change.
Single-trend reference · exploratory · per six months
- 1 · Jan 2019–Sep 2026×1.08Direction uncertain (serial pattern) · 66 zeros fitted as 1
Check the evidence
Interpretation and limitations (13)
- Exploratory description, not a forecast, causal explanation or proof of a change.
- Approximate 95% factor intervals assume independent, constant-variance log residuals and fixed boundaries. They do not account for boundary search, serial dependence or source revisions.
- Confirmed zeros are treated as 1 only for fitting and its diagnostics. Raw counts stay zero; low-count results depend on this convention.
- Independent phase lines may jump at boundaries. Every observation belongs to exactly one phase.
- Reporting, classifications and seasonality can change. Counts are not population-adjusted; a level shift without a slope change is not the target of this search.
- Uses dated last-good cached data, not newly verified source counts.
- 66 confirmed zeros fitted as 1; raw counts remain zero. Low-count trends are sensitive to this adjustment.
- The best candidate failed the residual-independence diagnostic. A single-trend reference is shown instead; this does not establish a stable trend.
- Serial pattern in residuals: independence is doubtful; the reported intervals may be too narrow. Seasonality is not modeled.
- 311 status is its value at retrieval, not at request creation. Newer cohorts have had less time to close; Open/Canceled comparisons can reflect workflow or cohort age rather than changing request volume.
- Current-system 311 coverage starts in 2019. Early phases may reflect adoption/reporting ramp-up; request counts are not completed work or incident prevalence.
- Many dependent filter conditions were searched. No multiple-testing-adjusted significance or causal attribution is claimed.
- Frequency compares fixed equal-length windows of raw counts, not population risk or a celeration-factor ratio. Reporting, classifications and exposure may have changed.
Phase diagnostics
| Phase | Start–end | Months | Factor / six months | Conditional 95% interval | Zeros fitted as 1 | Lag-one residual |
|---|---|---|---|---|---|---|
| 1 | January 2019–September 2026 | 93 | ×1.08 | 1.022–1.132 | 66 | 0.838 |
Exact monthly observations (120 slots)
| Month | Raw count | Coverage |
|---|---|---|
| September 2026 | 0 | complete |
| August 2026 | 1 | complete |
| July 2026 | 0 | complete |
| June 2026 | 1 | complete |
| May 2026 | 0 | complete |
| April 2026 | 1 | complete |
| March 2026 | 1 | complete |
| February 2026 | 2 | complete |
| January 2026 | 1 | complete |
| December 2025 | 0 | complete |
| November 2025 | 0 | complete |
| October 2025 | 0 | complete |
| September 2025 | 0 | complete |
| August 2025 | 2 | complete |
| July 2025 | 0 | complete |
| June 2025 | 1 | complete |
| May 2025 | 0 | complete |
| April 2025 | 1 | complete |
| March 2025 | 36 | complete |
| February 2025 | 47 | complete |
| January 2025 | 54 | complete |
| December 2024 | 52 | complete |
| November 2024 | 42 | complete |
| October 2024 | 30 | complete |
| September 2024 | 27 | complete |
| August 2024 | 44 | complete |
| July 2024 | 22 | complete |
| June 2024 | 14 | complete |
| May 2024 | 0 | complete |
| April 2024 | 0 | complete |
| March 2024 | 0 | complete |
| February 2024 | 0 | complete |
| January 2024 | 0 | complete |
| December 2023 | 0 | complete |
| November 2023 | 2 | complete |
| October 2023 | 0 | complete |
| September 2023 | 0 | complete |
| August 2023 | 0 | complete |
| July 2023 | 0 | complete |
| June 2023 | 0 | complete |
| May 2023 | 0 | complete |
| April 2023 | 2 | complete |
| March 2023 | 0 | complete |
| February 2023 | 0 | complete |
| January 2023 | 0 | complete |
| December 2022 | 0 | complete |
| November 2022 | 1 | complete |
| October 2022 | 0 | complete |
| September 2022 | 0 | complete |
| August 2022 | 0 | complete |
| July 2022 | 1 | complete |
| June 2022 | 0 | complete |
| May 2022 | 0 | complete |
| April 2022 | 0 | complete |
| March 2022 | 0 | complete |
| February 2022 | 0 | complete |
| January 2022 | 0 | complete |
| December 2021 | 0 | complete |
| November 2021 | 0 | complete |
| October 2021 | 0 | complete |
| September 2021 | 0 | complete |
| August 2021 | 0 | complete |
| July 2021 | 0 | complete |
| June 2021 | 0 | complete |
| May 2021 | 0 | complete |
| April 2021 | 0 | complete |
| March 2021 | 0 | complete |
| February 2021 | 0 | complete |
| January 2021 | 0 | complete |
| December 2020 | 1 | complete |
| November 2020 | 3 | complete |
| October 2020 | 11 | complete |
| September 2020 | 0 | complete |
| August 2020 | 0 | complete |
| July 2020 | 0 | complete |
| June 2020 | 0 | complete |
| May 2020 | 0 | complete |
| April 2020 | 0 | complete |
| March 2020 | 0 | complete |
| February 2020 | 0 | complete |
| January 2020 | 0 | complete |
| December 2019 | 0 | complete |
| November 2019 | 1 | complete |
| October 2019 | 0 | complete |
| September 2019 | 0 | complete |
| August 2019 | 0 | complete |
| July 2019 | 0 | complete |
| June 2019 | 0 | complete |
| May 2019 | 0 | complete |
| April 2019 | 0 | complete |
| March 2019 | 0 | complete |
| February 2019 | 0 | complete |
| January 2019 | 0 | complete |
| December 2018 | Unavailable | missing |
| November 2018 | Unavailable | missing |
| October 2018 | Unavailable | missing |
| September 2018 | Unavailable | missing |
| August 2018 | Unavailable | missing |
| July 2018 | Unavailable | missing |
| June 2018 | Unavailable | missing |
| May 2018 | Unavailable | missing |
| April 2018 | Unavailable | missing |
| March 2018 | Unavailable | missing |
| February 2018 | Unavailable | missing |
| January 2018 | Unavailable | missing |
| December 2017 | Unavailable | missing |
| November 2017 | Unavailable | missing |
| October 2017 | Unavailable | missing |
| September 2017 | Unavailable | missing |
| August 2017 | Unavailable | missing |
| July 2017 | Unavailable | missing |
| June 2017 | Unavailable | missing |
| May 2017 | Unavailable | missing |
| April 2017 | Unavailable | missing |
| March 2017 | Unavailable | missing |
| February 2017 | Unavailable | missing |
| January 2017 | Unavailable | missing |
| December 2016 | Unavailable | missing |
| November 2016 | Unavailable | missing |
| October 2016 | Unavailable | missing |
Source and reproducibility
- Publisher dataset
- 311 Service Requests · City of Chicago
- Source retrieved
- 2026-11-06T12:10:53.153Z
- Publisher update
- 2026-11-06T11:22:56.000Z
- Covered months
- January 2019–September 2026
- Source note
- Source v6vf-nfxy. Joint day/category/hour/applicable-flag/ward/status counts; no addresses, coordinates or incident identifiers. Each year's cells reconcile with an independent source total. Reads are not an atomic publisher snapshot. Current 311 system only, legacy_record=false; includes duplicate requests, not completed work. Status is as currently published, grouped by creation date—not historical status or completion date. Prepared daily community-area snapshot; scheduled rebuild at 06:00 America/Chicago. Full supported history is rechecked for corrections. Retrieval timestamps are preserved; this is not a real-time feed. Local indexed neighborhood snapshot. Totals are for the loaded area before other filters, not citywide totals. Citywide and unassigned-area views use a separate network-backed scope.
- Snapshot
- daily-v1:f761b44d-f9db-4d57-b536-48aea9b60f93:neighborhood-v2:fc9ab9a1c6c047fc660214b855284097
- Discovery method
- multi-feed-turn-and-frequency-renewal-v2
- Analyze method
- exploratory-segmented-log10-ols-zero-as-one-v3
- Search plan
- a3ffccedeb8d8ce18a30df3636839f775af1e5188e55a1f685695133135c6e35
- Evidence run
- 109b4859f9efbe7bdd758ffd66783ba908eba5bd982364c45f622cefb4bd551b
Challenge the pattern
Check unfiltered totals, comparable communities, source revisions and administrative definitions before treating this candidate as evidence of a real-world explanation. Only explicitly documented follow-ups above have been performed; no others are implied by the ranking. Browse the other graffiti requests candidates or review the complete screening method.