Expected Death Analysis

Covid-19 is causing a higher death rate than normal. There has been some controversy as to whether covid-19 was the cause of death, even if it was present in the deceased. To avoid this controversy, it's possible to just look at the number of deaths in a particular week and compare it with the number the same week over the past few years. (See, for example, Mortality surveillance during the COVID-19 pandemic in the Bulletin of the World Health Organization, New York Times A Positive Covid Milestone. ) The graph below uses data from the CDC ( JSON). In particular, the week of reported deaths and the percentage of expected deaths fields are used. The percent of expected deaths compares the death count in the particular week to the average for that week in 2017 throgh 2019. Comparing to same week data for previous years removes seasonal effects on death rates.

There is also an interesting analysis in the New York Times. The NYT analysis shows the consistently improving death rate (deaths per 100,000 population) until 2020. Analysis of death rates is interesting since there are so many variables. The number of deaths per 100,000 population is considerably less than half of what it was in 1920, probably due to medical advances. Other effects on the death rate include the age of the population, the expected lifespan of the population, and many other effects. The NYT article also has a chart comparing the death rate to the previous year showing a substantial increase in 2020.

As can be seen in the raw CDC data through March 14, 2020, this number is pretty stable. However, after March 14, we see the percentage of expected deaths increase dramatically. Towards the end of the dataset, the percentage of expected deaths is very low. This is because the CDC records the actual date of the death, but may not receive that report for several weeks. We can make predictions based on early reports (see below).

Causes of an increase in the number of deaths include an increase in disease caused deaths, an increase in population, and an aging population. Because the below graph based on CDC data compares deaths each week to the average for that week in the years 2017 through 2019, we expect an increase due to population increase and an aging population.

Using total US population data from here, we find the percentage population increase for years 2020 through 2022 compared to the average population in the years 2017 through 2019.
YearUS Population
2017329,791,231
2018332,140,037
2019334,319,671
Average332,083,600
Comparing the population in successive years to the average for 2017 through 2019, we get the table below.
YearUS PopulationIncrease Over 2017-2019
2020335,942,0033,858,4031.2%
2021336,997,6244,914,0241.5%
2022338,289,8576,206,2571.9%
2023339,996,5637,912,9632.4%
We expect a minor increase (less than 2.5%) in the number of deaths compared to those in 2017 through 2019 due to US population increase.

Due to the "baby boom" following World War 2, we expect an increase in the number of deaths from an aging population. According to CDC data , the average lifespan at birth for people born in 1950 was 68.2 years. CDC data shows US births for each year. The table below shows the number of people expected to die in recent years based on an expected lifespan of 68 years.
Year of Expected DeathBirth YearBirths, Expected Deaths
201719493,649,000
201819503,632,000
201919513,820,000
202019523,909,000
202119533,959,000
202219544,071,000
202319554,097,000
202419564,210,000
202519574,300,000
Averaging the number of deaths expected in 2017 through 2019 based on births in 1949 through 1951, we get 3,700,333 expected deaths. Due to the increased birth rates continuing from 1952, we expect increased deaths from 2020 through 2023 as shown below. Expected Deaths in the table below is based on the number of births 68 years earlier.
YearExpected DeathsExcess of 2017-2019 Expected Deaths
20203,909,000208,6675.6%
20213,959,000258,6677.0%
20224,071,000370,66710.0%
20234,097,000396,66710.7%
20244,210,000509,66713.8%
20254,300,000599,66716.2%

As suggested above, we expect an increase in the number of deaths due to an increasing population, an aging population, and disease. The table below summarizes the percentage increase in deaths over that in the years 2017 through 2019 due to population increase and an aging population (increased deaths due to increased births 68 years earlier).
Increase Over 2017-2019 Due To
YearPopulation IncreaseAging Popluation
20201.2%5.6%
20211.5%7.0%
20221.9%10.0%
20232.4%10.7%
In the year 2020, based on the table above, we expect about a 6.8% increase in deaths over 2017 through 2019 due to population increase and population aging. The graph below shows that in that year the increase in deaths substantially increased above this number, peaking at 43% over the expected deaths during the week of April 10. Looking at the year 2023, we expect about a 13.1% increase in deaths over 2017 through 2019 due to population increase and population aging. Though a bit early to tell at this writing (March 2023), it appears the excess death rate (over 2017-2019) is running in this area. As such, the contribution due to unusual disease such as covid 19 may be over. Not considered in this analysis, however, would be a decrease in future deaths due to deaths occuring earlier than expected (you only die once).

According to this document at medium.com, the timeline for infections ending in death averages as below:

Case counts (especially cases per 100,000 population) are a leading indicator. An increase in case counts is likely to result in an increase in deaths a couple months later. However, with vaccination and improved treatment, I expect the ratio of deaths to cases to decrease over time.

To Date Summary

The table below shows the actual number of reported deaths since 1/1/20, the expected nmber of deaths, and the excess number of deaths. As discussed above, the expected number is based on the same period for the years 2017 through 2019.

Predictions Based On Early Reports

As discussed above, it takes several weeks for the CDC to receive all the death reports for a specific week. In an attempt to get more current data, a "correction factor" has been developed based on how the percent expected deaths increases after the week of death as more reports are received. Data on report delays has been gathered from June 15, 2020 through May 29, 2021. This data is here. The summary data used for the predictions is here. The "Average Percent of Max" (not really shown as percent; 1.00 = 100%) is the portion of the final value that shows up the specified number of days after the end of the week of the death. The "final value" is the maximum value over time for that weeek as additional reports arrive at the CDC. The reported CDC percent of expected deaths is divided by the Average Percent of Max for the number of days between the end of the week of death and the CDC update date to yield the predicted percent of expected deaths. Based on this data, a predicted percentage of expected deaths is determined immediately following the week of death. As the CDC updates their numbers (every weekday), the correction factors are updated and the predicted percentage of expected deaths is updated. Along with a prediction based on the average correction factor, predictions are made based on the minimum and maximum prediction factors. These are the minimum percentage of final value the specified number of days after the end of week of the reported deaths and the maximum percentage of final value. Data is included in the prediction factor calculations once the percentage of expected deaths as reported by the CDC is unchanged for a week (making it appear this close to the final value). NOTE that the predicated values depend upon consistent reporting rates. If data to the CDC arrives faster than it has in the past, the predicted values will be higher. A graph of the reporting delay is below.

Average Age at Time of Death

The CDC does not publish data revealing the average age at death each week. They do, however, make data available showing the total number of deaths in approximate 10 year age groups each week. This data is here (CSV).

In the graph below, this data is used to compute an average age at death for each week. Records are used where the following conditions are satisfied:

The number of deaths in each age group is multiplied by the average age of that group (for example, the group 25-34 years uses an age of 30 years). These products are then added and divided by the total number of deaths in all age groups to yield an average age at death. Note that the age used for the 85 and older group is 90 years, the average in an 85 to 94 age group. Because the chart is not comparing age at time of death to historic values as the Percent of Expected Deaths chart, above, is, there may be seasonal effects that influence the chart.

Left drag mouse over area to zoom to that area; right click to zoom back to full

At first, I was expecting the age at death to decrease due to covid-19. We could then say covid-19 has resulted in so many years loss of life. However, it appears that covid-19 has, instead, just upset the balance in the number of deaths between different age groups. It has caused more older people to die causing the average age at time of death to increase. When percentage of expected deaths peaked in April 2020, the average age at death also peaked. When the percentage of expected deaths decreased in June 2020, fewer elderly were dying, so the average age at death also decreased. Then, as the percentage of expected deaths increased in July 2020, the average age at death also increased.

It's interesting to compare this with other data. For example, the life expectancy for someone born today in the US is about 78.539 years (as of 2018). However, people dying today were not born today, so today's life expectancy is not appropriate. We might look at the median age of the US population (38.2 years according to Wikipedia. We could then look at the life expectancy for those born in 1982. The life expectancy chart shows a life expectancy of 74.361 years for those born in 1982. That is still higher than the average age at death shown in the graph above. Looking at the graph above, we are seeing people die at about age 73. Thus they were born around 1947. Life expectancy for those born in 1950 is about 68.2 years according to this CDC document. The current 73 years is between the expected 68.2 years and the expected 74.361 years. As mentioned before, there are likely to be seasonal effects, but there is a fairly dramatic variation in age at death.

The image below demonstrates the average age at death calculation for February 1, 2020. It can be used to verify the average age at death calculations used to create the graph. The below calculation was done several months ago, and since then more data has shown up. This results in a slight difference between the below calculation and the data in the above graph. The graph above always uses the latest data.



Other Resources


Raw CDC Data

On 1/19/21, the CDC revised their website making it difficult to see the complete set of expected death data. The table below pulls the latest data from the CDC JSON data (https://data.cdc.gov/resource/r8kw-7aab.json). Note that the ending data is very low because it takes several weeks for the CDC to receive the death reports. The data below is based on the date of death, not the date the report is received. The percent of expected deaths will increase as more reports are received. The graph near the top of the page applies prediction factors to this data to yield a predicted percentage of expected deaths based on typical reporting delays.

CDC Data as of 04/11/2024

Week EndingPercent of Expected Deaths
01/04/202098.00
01/11/202097.00
01/18/202098.00
01/25/202099.00
02/01/202099.00
02/08/2020100
02/15/2020100
02/22/2020101.00
02/29/2020103.00
03/07/2020103.00
03/14/2020103.00
03/21/2020104.00
03/28/2020113.00
04/04/2020130.0
04/11/2020143.00
04/18/2020142.00
04/25/2020138.00
05/02/2020129.00
05/09/2020127.00
05/16/2020123.00
05/23/2020119.00
05/30/2020115.00
06/06/2020113.00
06/13/2020112.00
06/20/2020112.00
06/27/2020114.00
07/04/2020115.00
07/11/2020121.00
07/18/2020124.00
07/25/2020127.00
08/01/2020126.00
08/08/2020125.00
08/15/2020126.00
08/22/2020124.00
08/29/2020120.0
09/05/2020118.00
09/12/2020116.00
09/19/2020116.00
09/26/2020117.00
10/03/2020114.00
10/10/2020118.00
10/17/2020114.00
10/24/2020116.00
10/31/2020118.00
11/07/2020124.00
11/14/2020125.00
11/21/2020130.0
11/28/2020133.00
12/05/2020137.00
12/12/2020143.00
12/19/2020143.00
12/26/2020144.00
01/02/2021148.00
01/09/2021141.00
01/16/2021140.0
01/23/2021137.00
01/30/2021133.00
02/06/2021129.00
02/13/2021120.0
02/20/2021118.00
02/27/2021115.00
03/06/2021111.00
03/13/2021107.00
03/20/2021106.00
03/27/2021107.00
04/03/2021105.00
04/10/2021109.00
04/17/2021107.00
04/24/2021112.00
05/01/2021111.00
05/08/2021110.0
05/15/2021111.00
05/22/2021112.00
05/29/2021110.0
06/05/2021111.00
06/12/2021109.00
06/19/2021111.00
06/26/2021110.0
07/03/2021112.00
07/10/2021110.0
07/17/2021112.00
07/24/2021115.00
07/31/2021119.00
08/07/2021125.00
08/14/2021131.00
08/21/2021138.00
08/28/2021143.00
09/04/2021144.00
09/11/2021144.00
09/18/2021142.00
09/25/2021140.0
10/02/2021138.00
10/09/2021132.00
10/16/2021129.00
10/23/2021126.00
10/30/2021124.00
11/06/2021124.00
11/13/2021124.00
11/20/2021122.00
11/27/2021123.00
12/04/2021127.00
12/11/2021128.00
12/18/2021125.00
12/25/2021125.00
01/01/2022127.00
01/08/2022130.0
01/15/2022136.00
01/22/2022141.00
01/29/2022143.00
02/05/2022137.00
02/12/2022130.0
02/19/2022121.00
02/26/2022114.00
03/05/2022112.00
03/12/2022107.00
03/19/2022106.00
03/26/2022103.00
04/02/2022104.00
04/09/2022104.00
04/16/2022105.00
04/23/2022105.00
04/30/2022107.00
05/07/2022107.00
05/14/2022110.0
05/21/2022110.0
05/28/2022110.0
06/04/2022111.00
06/11/2022111.00
06/18/2022112.00
06/25/2022113.00
07/02/2022113.00
07/09/2022113.00
07/16/2022114.00
07/23/2022118.00
07/30/2022117.00
08/06/2022117.00
08/13/2022115.00
08/20/2022116.00
08/27/2022116.00
09/03/2022114.00
09/10/2022115.00
09/17/2022113.00
09/24/2022114.00
10/01/2022113.00
10/08/2022114.00
10/15/2022114.00
10/22/2022113.00
10/29/2022112.00
11/05/2022113.00
11/12/2022113.00
11/19/2022113.00
11/26/2022117.00
12/03/2022119.00
12/10/2022119.00
12/17/2022116.00
12/24/2022118.00
12/31/2022120.0
01/07/2023112.00
01/14/2023107.00
01/21/2023106.00
01/28/2023105.00
02/04/2023106.00
02/11/2023106.00
02/18/2023105.00
02/25/2023107.00
03/04/2023107.00
03/11/2023105.00
03/18/2023107.00
03/25/2023107.00
04/01/2023108.00
04/08/2023106.00
04/15/2023108.00
04/22/2023109.00
04/29/2023108.00
05/06/2023109.00
05/13/2023110.0
05/20/2023108.00
05/27/2023107.00
06/03/2023110.0
06/10/2023108.00
06/17/2023109.00
06/24/2023108.00
07/01/2023109.00
07/08/2023108.00
07/15/2023109.00
07/22/2023110.0
07/29/2023110.0
08/05/2023111.00
08/12/2023111.00
08/19/2023112.00
08/26/2023112.00
09/02/2023110.0
09/09/2023112.00
09/16/2023110.0
09/23/2023110.0
09/30/2023111.00
10/07/2023111.00
10/14/2023112.00
10/21/2023110.0
10/28/2023109.00
11/04/2023110.0
11/11/2023111.00
11/18/2023109.00
11/25/2023108.00
12/02/2023112.00
12/09/2023112.00
12/16/2023110.0
12/23/2023111.00
12/30/2023111.00
01/06/2024109.00
01/13/2024109.00
01/20/2024109.00
01/27/2024110.0
02/03/2024105.00
02/10/2024103.00
02/17/2024102.00
02/24/2024103.00
03/02/2024103.00
03/09/2024100
03/16/202497.00
03/23/202488.00
03/30/202472.00
04/06/202442.00


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