cmu-delphi · dshemetov · Jun 23, 2025 · Jun 23, 2025 · Jun 23, 2025 · Jun 23, 2025
diff --git a/docs/api/covidcast-signals/_source-template.md b/docs/api/covidcast-signals/_source-template.md
@@ -9,8 +9,7 @@ grand_parent: Main Endpoint (COVIDcast)
 
 * **Source name:** `SOURCE-API-NAME`
 * **Earliest issue available:** DATE RELEASED TO API
-* **Number of data revisions since 19 May 2020:** 0
-* **Date of last change:** Never
+* **Date of last data revision:** Never (see [data revision docs](#changelog))
 * **Available for:** county, hrr, msa, state (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [LICENSE NAME](../covidcast_licensing.md#APPLICABLE-SECTION)
@@ -21,6 +20,15 @@ A brief description of what this source measures.
 |---------------|----------------------------------------------------------------------------------------------------------|
 | `signal_name` | Brief description of the signal, including the units it is measured in and any smoothing that is applied |
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+Your collapsible content goes here. You can still use **Markdown** inside.
+
+</details>
+
 ## Table of contents
 {: .no_toc .text-delta}
 

diff --git a/docs/api/covidcast-signals/chng.md b/docs/api/covidcast-signals/chng.md
@@ -10,12 +10,22 @@ nav_order: 1
 
 * **Source name:** `chng`
 * **Earliest issue available:** November 4, 2020
-* **Number of data revisions since May 19, 2020:** 0
-* **Date of last change:** Never
+* **Date of last data revision:** Never (see [data revision docs](#changelog))
 * **Available for:** county, hrr, msa, state, hhs, nation (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [CC BY-NC](../covidcast_licensing.md#creative-commons-attribution-noncommercial)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+No changes so far.
+
+</details>
+
 ## Overview
 
 **Notice: This data source was inactive between 2021-10-04 and 2021-12-02 to allow us resolve some problems with the data pipeline. We have resumed daily updates and are working on a data patch to fill the gap. [Additional details on this inactive period are available below](#pipeline-pause).**

diff --git a/docs/api/covidcast-signals/covid-act-now.md b/docs/api/covidcast-signals/covid-act-now.md
@@ -9,13 +9,25 @@ nav_order: 2
 {: .no_toc}
 
 * **Source name:** `covid-act-now`
-* **Earliest issue available:** 2021-03-25
-* **Number of data revisions since 19 May 2020:** 0
-* **Date of last change:** Never
+* **Earliest issue available:** March 25, 2021
+* **Date of last data revision:** Never (see [data revision docs](#changelog))
 * **Available for:** county, hrr, msa, state, hhs, nation (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [CC BY-NC](../covidcast_licensing.md#creative-commons-attribution-noncommercial)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+No changes so far.
+
+</details>
+
+## Overview
+
 The [COVID Act Now (CAN)](https://covidactnow.org/) data source provides COVID-19 testing statistics, such as positivity rates and total tests performed.
 The county-level positivity rates and test totals are pulled directly from CAN using [their API](https://covidactnow.org/data-api).
 While CAN provides this data potentially from multiple sources, we only use data that CAN sources from the

diff --git a/docs/api/covidcast-signals/covid-trends-and-impact-survey.md b/docs/api/covidcast-signals/covid-trends-and-impact-survey.md
@@ -11,12 +11,41 @@ permalink: api/covidcast-signals/fb-survey.html
 
 * **Source name:** `fb-survey`
 * **Earliest issue available:** April 29, 2020
-* **Number of data revisions since May 19, 2020:** 1
-* **Date of last change:** [June 3, 2020](../covidcast_changelog.md#fb-survey)
+* **Date of last data revision:** June 3, 2020 (see [data revision docs](../covidcast_changelog.md#fb-survey))
 * **Available for:** county, hrr, msa, state, nation (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [CC BY](../covidcast_licensing.md#creative-commons-attribution)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+### June 3, 2020
+
+Duplicate survey weights had corrupted historical figures for the following signals and dates. The correct data has been restored to the API.
+* `raw_wcli`
+  * `county`: 20200406, 20200408, 20200410, 20200430
+  * `hrr`: 20200406, 20200408-20200410, 20200430
+  * `msa`: 20200408, 20200410, 20200430
+  * `state`: 20200408-20200410, 20200430
+* `smoothed_wcli`
+  * `county`: 20200406, 20200408-20200414, 20200430-20200506
+  * `hrr`: 20200406-20200415, 20200430-20200506
+  * `msa`: 20200408-20200414, 20200430-20200506
+  * `state`: 20200408-20200416, 20200430-20200506
+
+### November 20, 2020
+
+Due to a bug in our data processing system, estimates of the percentage of people reporting that they have been tested for COVID-19 calculated before October 8th were incorrect.
+We incorrectly treated an answer of “no” as a missing response, which affected the `smoothed_tested_14d` and `smoothed_wtested_14d` signals from the `fb-survey` source.
+
+As of Nov. 20th, the error has been corrected and all affected data reissued.
+
+</details>
+
 ## Overview
 
 This data source is based on the [COVID-19 Trends and Impact Survey (CTIS)](../../symptom-survey/)

diff --git a/docs/api/covidcast-signals/doctor-visits.md b/docs/api/covidcast-signals/doctor-visits.md
@@ -10,12 +10,22 @@ nav_order: 1
 
 * **Source name:** `doctor-visits`
 * **Earliest issue available:** April 29, 2020
-* **Number of data revisions since May 19, 2020:** 1
-* **Date of last change:** November 9, 2020
+* **Date of last data revision:** November 9, 2020 (see [data revision docs](#changelog))
 * **Available for:** county, hrr, msa, state (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [CC BY](../covidcast_licensing.md#creative-commons-attribution)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+### November 9, 2020
+We went from a custom geo-mapping file (for aggregating from county->(msa, hrr, state)) to a central geo file based on rigorously sourced US census data.
+
+</details>
 
 ## Overview
 

diff --git a/docs/api/covidcast-signals/dsew-cpr.md b/docs/api/covidcast-signals/dsew-cpr.md
@@ -9,13 +9,25 @@ nav_order: 2
 {: .no_toc}
 
 * **Source name:** `dsew-cpr`
-* **Earliest issue available:** 2022-01-28
-* **Number of data revisions since 19 May 2020:** 0
-* **Date of last change:** Never
+* **Earliest issue available:** January 28, 2022
+* **Date of last data revision:** Never (see [data revision docs](#changelog))
 * **Available for:** county, msa, state, hhs, nation (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [Public Domain US Government](https://www.usa.gov/government-works)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+No changes so far.
+
+</details>
+
+## Overview
+
 The Community Profile Report (CPR) is published by the Data Strategy and Execution Workgroup (DSEW) of the White House COVID-19 Team. For more information, see the [official description at healthdata.gov](https://healthdata.gov/Health/COVID-19-Community-Profile-Report/gqxm-d9w9) for "COVID-19 Community Profile Report". Each issue of the CPR is made available as an attachment on that page. You can view all attachments by scrolling to the bottom of the "About this dataset" panel and clicking "Show more".
 
 This data source provides various COVID-19 related metrics, of which we report hospital admissions and vaccinations. 

diff --git a/docs/api/covidcast-signals/ght.md b/docs/api/covidcast-signals/ght.md
@@ -10,11 +10,21 @@ nav_order: 2
 
 * **Source name:** `ght`
 * **Earliest issue available:** April 29, 2020
-* **Number of data revisions since May 19, 2020:** 0
-* **Date of last change:** Never
+* **Date of last data revision:** Never (see [data revision docs](#changelog))
 * **Available for:** dma, hrr, msa, state (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+No changes so far.
+
+</details>
+
 ## Overview
 
 This data source (`ght`) is based on Google searches, provided to us by Google

diff --git a/docs/api/covidcast-signals/google-survey.md b/docs/api/covidcast-signals/google-survey.md
@@ -10,12 +10,22 @@ nav_order: 2
 
 * **Source name:** `google-survey`
 * **Earliest issue available:** May 01, 2020
-* **Number of data revisions since May 19, 2020:** 0
-* **Date of last change:** Never
+* **Date of last data revision:** Never (see [data revision docs](#changelog))
 * **Available for:** county, hrr, msa, state (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [CC BY](../covidcast_licensing.md#creative-commons-attribution)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+No changes so far.
+
+</details>
+
 ## Overview
 
 Data source based on [Google-run symptom surveys](https://9to5google.com/2020/03/23/google-coronavirus-survey/), through publisher websites,

diff --git a/docs/api/covidcast-signals/google-symptoms.md b/docs/api/covidcast-signals/google-symptoms.md
@@ -10,12 +10,24 @@ nav_order: 1
 
 * **Source name:** `google-symptoms`
 * **Earliest issue available:** Aug 20, 2017
-* **Number of data revisions since May 19, 2020:** 1
-* **Date of last change:** February 28, 2025
+* **Date of last data revision:** March 14, 2025 (see [data revision docs](#changelog))
 * **Available for:** county, MSA, HRR, state, HHS, nation (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** To download or use the data, you must agree to the Google [Terms of Service](https://policies.google.com/terms)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+### March 14, 2025
+Google added earlier dates starting from 2017-08-15 and also fixed a gap of county-level data from November 14 2022 through February 20, 2023.
+
+### February 14, 2025
+We added a new signal s07_raw_search and s07_smoothed_search.
+
+</details>
+
 ## Overview
 
 This data source is based on the [COVID-19 Search Trends symptoms

diff --git a/docs/api/covidcast-signals/hhs.md b/docs/api/covidcast-signals/hhs.md
@@ -10,12 +10,24 @@ nav_order: 2
 
 * **Source name:** `hhs`
 * **Earliest issue available:** November 16, 2020
-* **Number of data revisions since 19 May 2020:** 0
-* **Date of last change:** Never
+* **Date of last data revision:** Never (see [data revision docs](#changelog))
 * **Available for:** state, hhs, nation (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [Public Domain US Government](https://www.usa.gov/government-works)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+No changes so far.
+
+</details>
+
+## Overview
+
 The U.S. Department of Health & Human Services (HHS) publishes several
 datasets on patient impact and hospital capacity. The data is made available
 to HHS through the CDC’s National Healthcare Safety Network (NHSN). One of these

diff --git a/docs/api/covidcast-signals/hospital-admissions.md b/docs/api/covidcast-signals/hospital-admissions.md
@@ -10,12 +10,23 @@ nav_order: 1
 
 * **Source name:** `hospital-admissions`
 * **Earliest issue available:** June 21, 2020
-* **Number of data revisions since May 19, 2020:** 1
-* **Date of last change:** October 20, 2020
+* **Date of last data revision:** October 20, 2020 (see [data revision docs](#changelog))
 * **Available for:** county, hrr, msa, state (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [CC BY](../covidcast_licensing.md#creative-commons-attribution)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+### October 20, 2020
+We went from a custom geo mapping file (for aggregating from zip->(county, msa, hrr, state)) to a central geo file based on rigorously sourced US census data.
+
+</details>
+
 ## Overview
 
 This data source is based on electronic medical records and claims data about

diff --git a/docs/api/covidcast-signals/indicator-combination.md b/docs/api/covidcast-signals/indicator-combination.md
@@ -22,12 +22,30 @@ calculated or composed by Delphi. It is not a primary data source.
 ## Statistical Combination Signals
 
 * **Earliest issue available:** May 20, 2020
-* **Number of data revisions since May 19, 2020:** 1
-* **Date of last change:** [June 3, 2020](../covidcast_changelog.md#indicator-combination)
+* **Date of last data revision:** June 3, 2020 (see [data revision docs](#changelog))
 * **Available for:** county, msa, state (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 * **License:** [CC BY](../covidcast_licensing.md#creative-commons-attribution)
 
+## Changelog
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+### June 3, 2020
+
+Standard errors are now included in the `nmf_day_doc_fbc_fbs_ght` signal for all geo levels and dates, representing the estimated uncertainty in this signal. This uncertainty comes because the signal is a combination of other signals based on survey estimates or other estimates with margins of error.
+
+* `nmf_day_doc_fbc_fbs_ght`
+  * all geo levels
+    * all dates
+
+</details>
+
+## Overview
+
 These signals combine Delphi's indicators---*not* including cases and deaths,
 but including other signals expected to be related to the underlying rate of
 coronavirus infection---to produce a single indicator. The goal is to provide a
@@ -191,12 +209,27 @@ The resampling method for each input source is as follows:
 
 ## Compositional Signals: Confirmed Cases and Deaths
 
-* **Earliest issue available:** 7 July 2020
-* **Number of data revisions since 19 May 2020:** 1
-* **Date of last change:** [12 October 2020](../covidcast_changelog.md#indicator-combination)
+* **Earliest issue available:** July 7, 2020
+* **Date of last data revision:** October 12, 2020 (see [data revision docs](#changelog-deaths))
 * **Available for:** county, msa, hrr, state (see [geography coding docs](../covidcast_geography.md))
 * **Time type:** day (see [date format docs](../covidcast_times.md))
 
+## Changelog Deaths
+
+<details>
+<summary>Click to expand</summary>
+
+See [COVIDcast Signal Changes](../covidcast_changelog.md) for general information about how we track changes to signals.
+
+### October 12, 2020
+
+The 10 October 2020 issue of all `indicator-combination` deaths signals has been removed from the API. These signals are primarily constructed of USAFacts data, whose 10 October 2020 issue was discovered to be corrupt on 11 October and repaired on 12 October. Subsequent issues have adequate coverage of all regions and dates included in the 10 October issue, so this change only affects forecasters who intend to pull training data with an `as_of` or `issues` parameter set to 20201010.
+
+</details>
+
+
+## Overview
+
 These signals combine the cases and deaths data from JHU and USA Facts. This is
 a straight composition: the signals below use the [JHU signal data](jhu-csse.md)
 for Puerto Rico, and the [USA Facts signal data](usa-facts.md) everywhere else.