Having built a model to forecast the future progression of coronavirus in different geographical locations, and calibrated assumptions to match the UK experience, I regularly check the forecasts against reported figures.

In the UK there are several different sources for coronavirus related data. The headline figures (those with greatest media focus) are published alongside the government’s daily press conference. Slightly unhelpfully, the government changed their definition of deaths on 29 April 2020 – moving from UK hospital deaths (although, peculiarly, the definition also included non-hospital deaths outside England) to “all-settings” deaths across the UK. The change to “all-settings” does make sense because it encompasses more COVID-19 deaths.

However, there is a further set of UK deaths figures, from the Office of National Statistics, these provide an even more complete picture of COVID-19 deaths. Unlike the Public Heath England deaths, used in the government’s press briefings, which only include positive tests, the ONS figures include all deaths where COVID-19 is mentioned on the death certificate (as described in this well written explanation). The ONS figures are published weekly, and there is a time lag, but they are the probably the best data source.

The government have been including the ONS figures, weekly, labelled as “all settings” deaths in their press briefings. But, confusingly, they now call the PHE data “all settings” deaths – even though the definitions are different.

A further issue with deaths reported at the UK press briefings is that they are shown for the day that the death is reported. This can be helpful for quickly seeing the trend in deaths – but isn’t ideal for analysis, because a reported death may have occurred weeks beforehand. Date of death data is preferable for analysis – but deaths from the most recent days are unlikely to be fully reported. NHS England provide date of death data.

I’ve compared my model against the different data sources to establish its accuracy as follows:

1. Comparison against government reported figures 6 May 2020

The first graph shows my model’s daily forecast against the government’s reported “all settings” figures. The reported figures are volatile from day to day, so it’s not easy to see the full trend.

Using a 7 day rolling average better illustrates the trend

The graph above shows the cumulative reported death figures compared to the forecast. The model is tracking above the reported figures. However, I’ve also included the weekly ONS data on this graph (the black dots), which has a wider definition of COVID-19 deaths, the last of which (17 April 2020) was above both my model and the reported all-settings data.

2. NHS data of death data

NHS England publish date of death data for hospital deaths in England. I’ve adapted my model for England (rather than UK) by adjusting the starting population to 56 million, and reducing the number of imported cases – to produce the following comparison:

These show hospital only deaths, without the reporting lag, from my model to compare with date-of-death figures. Deaths from most recent days wont yet be reported, which is one reason why the model produces higher figures for most recent dates.

I set out the actual numbers for these graphs, and future forecasts, below. These all assume the current UK full lockdown continues:

Date	Total deaths model (all settings)	Total reported deaths (PHE all settings)	Total reported deaths ONS (all settings)	Daily deaths model (all deaths)	Daily reported (PHE all settings)
08/03/2020	19	2		4	0
09/03/2020	25	3		6	1
10/03/2020	32	7		7	4
11/03/2020	41	7		9	0
12/03/2020	52	9		11	2
13/03/2020	65	10		13	1
14/03/2020	82	28		17	18
15/03/2020	102	43		20	15
16/03/2020	127	65		25	22
17/03/2020	158	81		31	16
18/03/2020	196	115		38	34
19/03/2020	242	158		46	43
20/03/2020	298	194		56	36
21/03/2020	367	250		69	56
22/03/2020	451	285		84	35
23/03/2020	554	359		103	74
24/03/2020	679	508		125	149
25/03/2020	832	694		153	186
26/03/2020	1018	877		186	183
27/03/2020	1245	1161		226	284
28/03/2020	1518	1455		274	294
29/03/2020	1847	1669		329	214
30/03/2020	2240	2043		393	374
31/03/2020	2705	2425		464	382
01/04/2020	3246	3095		542	670
02/04/2020	3869	3747		623	652
03/04/2020	4573	4461	4526	704	714
04/04/2020	5356	5221		783	760
05/04/2020	6210	5865		854	644
06/04/2020	7125	6433		916	568
07/04/2020	8090	7471		965	1038
08/04/2020	9090	8505		1000	1034
09/04/2020	10112	9608		1022	1103
10/04/2020	11144	10760	11413	1032	1152
11/04/2020	12175	11599		1031	839
12/04/2020	13197	12285		1022	686
13/04/2020	14203	13029		1006	744
14/04/2020	15190	14073		987	1044
15/04/2020	16156	14915		965	842
16/04/2020	17099	15944		943	1029
17/04/2020	18018	16879	20909	920	935
18/04/2020	18916	17994		897	1115
19/04/2020	19790	18492		875	498
20/04/2020	20643	19051		853	559
21/04/2020	21474	20223		831	1172
22/04/2020	22284	21060		810	837
23/04/2020	23073	21787		789	727
24/04/2020	23841	22792		768	1005
25/04/2020	24589	23635		748	843
26/04/2020	25317	24055		728	420
27/04/2020	26026	24393		708	338
28/04/2020	26714	25302		689	909
29/04/2020	27384	26097		670	795
30/04/2020	28034	26771		651	674
01/05/2020	28667	27510		632	739
02/05/2020	29281	28131		614	621
03/05/2020	29877	28446		596	315
04/05/2020	30456	28734		579	288
05/05/2020	31018			562
06/05/2020	31563			545
07/05/2020	32092			529
08/05/2020	32605			513
09/05/2020	33103			497
10/05/2020	33585			482
11/05/2020	34052			467
12/05/2020	34505			453
13/05/2020	34944			439
14/05/2020	35369			425
15/05/2020	35781			412
16/05/2020	36180			399
17/05/2020	36566			386
18/05/2020	36939			374
19/05/2020	37301			362
20/05/2020	37651			350
21/05/2020	37989			339
22/05/2020	38317			327
23/05/2020	38634			317
24/05/2020	38940			306
25/05/2020	39236			296
26/05/2020	39523			286
27/05/2020	39800			277
28/05/2020	40067			268
29/05/2020	40326			259
30/05/2020	40576			250
31/05/2020	40817			242
01/06/2020	41051			233
02/06/2020	41276			226
03/06/2020	41494			218
04/06/2020	41705			210
05/06/2020	41908			203
06/06/2020	42104			196
07/06/2020	42294			190
08/06/2020	42477			183
09/06/2020	42653			177
10/06/2020	42824			171
11/06/2020	42989			165
12/06/2020	43148			159
13/06/2020	43301			153
14/06/2020	43449			148
15/06/2020	43592			143
16/06/2020	43730			138
17/06/2020	43864			133
18/06/2020	43992			129
19/06/2020	44116			124
20/06/2020	44236			120
21/06/2020	44351			115
22/06/2020	44463			111
23/06/2020	44570			108
24/06/2020	44674			104
25/06/2020	44774			100
26/06/2020	44871			97
27/06/2020	44964			93
28/06/2020	45054			90
29/06/2020	45140			87
30/06/2020	45224			84
01/07/2020	45304			81
02/07/2020	45382			78
03/07/2020	45457			75
04/07/2020	45530			72
05/07/2020	45600			70
06/07/2020	45667			67
07/07/2020	45732			65
08/07/2020	45794			63
09/07/2020	45855			60
10/07/2020	45913			58
11/07/2020	45969			56
12/07/2020	46024			54
13/07/2020	46076			52
14/07/2020	46126			50
15/07/2020	46175			49
16/07/2020	46222			47
17/07/2020	46267			45
18/07/2020	46311			44
19/07/2020	46353			42
20/07/2020	46394			41
21/07/2020	46433			39
22/07/2020	46471			38
23/07/2020	46507			36
24/07/2020	46542			35
25/07/2020	46576			34
26/07/2020	46609			33
27/07/2020	46641			32
28/07/2020	46671			30
29/07/2020	46701			29
30/07/2020	46729			28
31/07/2020	46756			27
01/08/2020	46783			26
02/08/2020	46808			26
03/08/2020	46833			25
04/08/2020	46857			24
05/08/2020	46880			23
06/08/2020	46902			22
07/08/2020	46923			21
08/08/2020	46944			21
09/08/2020	46964			20
10/08/2020	46983			19
11/08/2020	47002			19
12/08/2020	47019			18
13/08/2020	47037			17
14/08/2020	47054			17
15/08/2020	47070			16
16/08/2020	47085			16
17/08/2020	47100			15
18/08/2020	47115			15
19/08/2020	47129			14
20/08/2020	47143			14
21/08/2020	47156			13
22/08/2020	47168			13
23/08/2020	47181			12
24/08/2020	47192			12
25/08/2020	47204			11
26/08/2020	47215			11
27/08/2020	47226			11
28/08/2020	47236			10
29/08/2020	47246			10
30/08/2020	47256			10
31/08/2020	47265			9
01/09/2020	47274			9
02/09/2020	47283			9
03/09/2020	47292			9
04/09/2020	47300			8
05/09/2020	47308			8
06/09/2020	47316			8
07/09/2020	47323			7
08/09/2020	47330			7
09/09/2020	47337			7
10/09/2020	47344			7
11/09/2020	47351			7
12/09/2020	47357			6
13/09/2020	47363			6
14/09/2020	47369			6
15/09/2020	47375			6
16/09/2020	47381			6
17/09/2020	47386			5
18/09/2020	47392			5
19/09/2020	47397			5
20/09/2020	47402			5
21/09/2020	47407			5
22/09/2020	47412			5
23/09/2020	47416			5
24/09/2020	47421			4
25/09/2020	47425			4
26/09/2020	47429			4
27/09/2020	47433			4
28/09/2020	47437			4
29/09/2020	47441			4
30/09/2020	47445			4
01/10/2020	47449			4
02/10/2020	47453			4
03/10/2020	47456			4
04/10/2020	47459			3
05/10/2020	47463			3
06/10/2020	47466			3
07/10/2020	47469			3
08/10/2020	47472			3
09/10/2020	47475			3
10/10/2020	47478			3
11/10/2020	47481			3