scholarly journals Randomised Badger Culling Trial: Impact, based on more extensive data

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Health Agency ◽  
Outer Ring ◽  
Final Report ◽  
Extensive Data ◽  
Badger Culling ◽  
Or Groups ◽  
Scientific Group ◽  
Surrounding Areas ◽  
The Uk ◽  
The Impact

In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of the Randomised Badger Culling Trial (RBCT). Badgers were culled between 1998 and 2005 across 100 km2 (nominal) zones in the West of England. The results were based on a model of confirmed New Herd Incidence (NHI). It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence in surrounding areas. This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates the data. The Animal and Plant Health Agency supplied this data in March 2016. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence. Whilst the proactive culls substantially reduced confirmed NHI in treated areas, such culls did not significantly increase NHI in the surrounding outer ring. In fact, between 1998 and 2012 these NHI slightly reduced in the outer ring . Between 2006 and 2012 they dropped by 28%, 1% and 18% in the treated, outer 2km ring, and combined areas respectively. Based on the total number of confirmed NHIs prevented between 1998 and 2012, a break-even cost to complete a badger removal exercise was calculated to be £8,693 per km2 with benefits continuing in 2012. Proactive culling only reduced confirmed NHIs with no significant impact on unconfirmed NHIs. The more limited reactive culls had no impact on both the treated area and the outer 2km ring. Conclusions in the RBCT Final Report, which were based on the results of a model of time-shifted early data, poorly reflect the overall greater benefits seen in this more extensive data. Badger culling is highly contentious in the UK and many press reports adversely report the effectiveness of badger culling in general and the culls which started in 2013 in particular. The RBCT conclusions are often cited to add credence to these press reports. After the first year of substantial culling in the RBCT, this work found that 9 years of data were needed to clearly see the full extent by which TB dropped when plotted against calendar year. This delay should be reflected on when accounting for the circumstances and assessing impact of the 2013 culls. This work was restricted to looking at data showing total TB breakdowns over all zones. Further work to examine breakdowns by zone or groups of zones may reveal more.

scholarly journals Randomised Badger Culling Trial: Impact, based on more extensive data

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Health Agency ◽  
Outer Ring ◽  
Final Report ◽  
Extensive Data ◽  
Badger Culling ◽  
Or Groups ◽  
Scientific Group ◽  
Surrounding Areas ◽  
The Uk ◽  
The Impact

In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of the Randomised Badger Culling Trial (RBCT). Badgers were culled between 1998 and 2005 across 100 km2 (nominal) zones in the West of England. The results were based on a model of confirmed New Herd Incidence (NHI). It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence in surrounding areas. This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates the data. The Animal and Plant Health Agency supplied this data in March 2016. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence. Whilst the proactive culls substantially reduced confirmed NHI in treated areas, such culls did not significantly increase NHI in the surrounding outer ring. In fact, between 1998 and 2012 these NHI slightly reduced in the outer ring . Between 2006 and 2012 they dropped by 28%, 1% and 18% in the treated, outer 2km ring, and combined areas respectively. Based on the total number of confirmed NHIs prevented between 1998 and 2012, a break-even cost to complete a badger removal exercise was calculated to be £8,693 per km2 with benefits continuing in 2012. Proactive culling only reduced confirmed NHIs with no significant impact on unconfirmed NHIs. The more limited reactive culls had no impact on both the treated area and the outer 2km ring. Conclusions in the RBCT Final Report, which were based on the results of a model of time-shifted early data, poorly reflect the overall greater benefits seen in this more extensive data. Badger culling is highly contentious in the UK and many press reports adversely report the effectiveness of badger culling in general and the culls which started in 2013 in particular. The RBCT conclusions are often cited to add credence to these press reports. After the first year of substantial culling in the RBCT, this work found that 9 years of data were needed to clearly see the full extent by which TB dropped when plotted against calendar year. This delay should be reflected on when accounting for the circumstances and assessing impact of the 2013 culls. This work was restricted to looking at data showing total TB breakdowns over all zones. Further work to examine breakdowns by zone or groups of zones may reveal more.

scholarly journals Randomised Badger Culling Trial: Impact, based on more extensive data

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Health Agency ◽  
Final Report ◽  
Extensive Data ◽  
Badger Culling ◽  
Or Groups ◽  
Scientific Group ◽  
Surrounding Areas ◽  
The Uk ◽  
The Cost ◽  
The Impact

In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of the Randomised Badger Culling Trial (RBCT). Badgers were culled between 1998 and 2005 across 100 km2 (nominal) zones in the West of England. The results were based on a model of New Herd Incidence (NHI). It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence in surrounding areas. This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates the data. The Animal and Plant Health Agency supplied this data in March 2016. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence. Whilst the proactive culls substantially and sustainably reduced cattle TB in treated areas, such culls did not significantly increase TB in the surrounding areas. NHIs between 2006 and 2012 dropped by 28%, 1% and 18% in the treated, outer 2km ring, and combined areas respectively. Based on the number of NHIs prevented since 1998 in the combined area, a break-even cost to complete a badger removal exercise was calculated to be £8,693 per km2. This figure may be under-estimated because it takes no account of any NHIs prevented after 2012. The more limited reactive culls had no impact on both the treated area and outer 2km ring. Proactive culling only reduced confirmed TB with no significant impact on unconfirmed TB. Conclusions in the RBCT Final Report, which were based on the results of a model of time-shifted early data, poorly reflect the overall greater benefits seen in this more extensive data. Badger culling is highly contentious in the UK and many press reports adversely report the effectiveness of badger culling in general and the culls which started in 2013 in particular. The RBCT conclusions are often cited to add credence to these press reports. After the first year of substantial culling in the RBCT, this work found that 9 years of data were needed to clearly see the full extent by which TB dropped when plotted against calendar year. This delay should be reflected on when accounting for the circumstances and assessing impact of the 2013 culls. This work was restricted to looking at data showing total TB breakdowns over all zones. Further work to examine breakdowns by zone or groups of zones may reveal more.

scholarly journals Randomised Badger Culling Trial: Impact, based on more extensive data

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Health Agency ◽  
Final Report ◽  
Extensive Data ◽  
Badger Culling ◽  
Or Groups ◽  
Scientific Group ◽  
Surrounding Areas ◽  
The Uk ◽  
The Cost ◽  
The Impact

In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of the Randomised Badger Culling Trial (RBCT). Badgers were culled between 1998 and 2005 across 100 km2 (nominal) zones in the West of England. The results were based on a model of New Herd Incidence (NHI). It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence in surrounding areas. This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates the data. The Animal and Plant Health Agency supplied this data in March 2016. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence. Whilst the proactive culls substantially and sustainably reduced cattle TB in treated areas, such culls did not significantly increase TB in the surrounding areas. In fact NHIs between 2006 and 2012 dropped by 28%, 1% and 18% in the treated, outer 2km ring, and combined areas respectively. Based on the number of NHIs prevented since 1998, a break-even cost to complete a badger removal exercise was calculated to be £8,693 per km2. This figure may be under-estimated because it takes no account of any NHIs prevented after 2012. The more limited reactive culls had no impact on both the treated area and outer 2km ring. Proactive culling only reduced confirmed TB with no significant impact on unconfirmed TB. Conclusions in the RBCT Final Report, which were based on the results of a model of time-shifted early data, poorly reflect the greater benefits seen in this more extensive data. Badger culling is highly contentious in the UK and many press reports adversely report the effectiveness of badger culling in general and the culls which started in 2013 in particular. Unfortunately the RBCT conclusions are often cited to add credence to these press reports. In the RBCT, after the first year of substantial culling, this work found that 9 years of data were needed to clearly see the full extent by which TB dropped when plotted against calendar year. The impact of the culls, which started in late 2013, may not become clear until late 2023 after a 2-year reporting delay. This work was restricted to looking at data showing total TB breakdowns over all triplets. Further work to examine breakdowns by triplet or groups of triplets should reveal more.

scholarly journals Randomised Badger Culling Trial: Impact based on more extensive data

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Health Agency ◽  
First Year ◽  
Final Report ◽  
Incidence Data ◽  
Badger Culling ◽  
Scientific Group ◽  
Surrounding Areas ◽  
The Uk ◽  
The Cost ◽  
The Impact

In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of a trial where badgers were culled between 1998 and 2005. This trial, known as the Randomised Badger Culling Trial (RBCT), was performed across 100 km2 (nominal) zones in the West of England. The results were based on a model of new herd incidence data. It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence in surrounding areas. This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates the data. The Animal and Plant Health Agency supplied this data in March 2016. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence. Whilst the proactive culls substantially and sustainably reduced cattle TB in treated areas, such culls did not significantly increase TB in the surrounding areas. In fact New Herd Incidents (NHI’s) between 2006 and 2012 dropped by 28%, 1% and 18% in the treated, outer 2km ring, and combined areas respectively. Based on the number of NHI’s prevented since 1998, a break-even cost to complete a badger removal exercise was calculated to be £8,454 per km2. This figure may be under-estimated because it takes no account of any NHI’s prevented after 2012. The more limited reactive culls were found to have no significant impact. This applied to both the treated area and outer 2km ring. The data also showed that the culls only reduced confirmed TB with no significant impact on unconfirmed TB. This was also found by the ISG when they reported results in 2007. Conclusions in the RBCT final report were made based on incomplete data so are poorly grounded. In addition to this, many mass media outlets are already adversely reporting the impact for culls which started in South West England in 2013. In the RBCT, after the first year of substantial culling, 9 years of data were needed to clearly see the full extent by which TB dropped when the data was not time-shifted. It is likely that the impact of the 2013 culls will not become clear until sometime between 2020 and 2025.

scholarly journals Bovine tuberculosis in cattle from 1986 to 2012 in and around badger-culled areas of the RBCT

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Bovine Tuberculosis ◽  
Health Agency ◽  
Incidence Data ◽  
Badger Culling ◽  
Scientific Group ◽  
Surrounding Areas ◽  
The Uk ◽  
The Cost ◽  
The Impact ◽  
South West England

In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of a trial where badgers were culled between 1998 and 2005. This trial, known as the Randomised Badger Culling Trial (RBCT), was performed across 100 km2 (nominal) zones in the West of England. The results were based on a model of new herd incidence data. It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence on neighbouring farms. This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates data supplied in March 2016 by the Animal and Plant Health Agency. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence. It appears that whilst cattle TB noticeably reduced in areas subjected to proactive culling, TB did not significantly increase in the surrounding areas. The more limited reactive culls were found to have no significant impact either positively or negatively. This applied to both the treated and surrounding areas. The more extensive data also showed that culling badgers only reduced confirmed TB with no significant impact on unconfirmed TB. This was also found by the ISG in 2007 when using their model. The delay before culling benefit became apparent was about 5 years after the first substantial cull. This has implications for the culls which started in South West England in 2013. If account is taken for the need to average the data, the number of years needed to see TB drop, and the reporting delay, it may not be until September 2023 before the impact of these culls become clear. Also, if culls stop after year four in each zone, this risks benefits falling short of those achieved in the RBCT.

scholarly journals Bovine tuberculosis in cattle from 1986 to 2012 in and around badger-culled areas of the RBCT

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Bovine Tuberculosis ◽  
Health Agency ◽  
Incidence Data ◽  
Badger Culling ◽  
Media Hype ◽  
Scientific Group ◽  
Surrounding Areas ◽  
The Uk ◽  
The Cost ◽  
The Impact

In 2007 the Independent Scientific Group (ISG) reported to the UK government the impact on bovine tuberculosis (TB) in cattle of a trial where badgers were culled between 1998 and 2005. This trial, known as the Randomised Badger Culling Trial (RBCT), was performed across 100 km2 (nominal) zones in the West of England. The results were based on a model of new herd incidence data. It was concluded that reactive culling generated overall detrimental effects, while proactive culling achieved very modest overall benefits at the cost of elevated incidence in surrounding areas. This work looks at more extensive RBCT data to examine if these findings hold true. Instead of presenting the results of a model, this work directly illustrates the data. The Animal and Plant Health Agency supplied this data in March 2016. Such data covers a greater number of years (1986 to 2012) and includes the prevalence of herd restrictions as well as herd incidence. Whilst the proactive culls substantially and sustainably reduced cattle TB in treated areas, such culls did not significantly increase TB in the surrounding areas. In fact New Herd Incidents (NHI’s) between 2006 and 2012 dropped by 28%, 1% and 18% in the treated, outer 2km ring, and combined areas respectively. Based on the number of NHI’s prevented since 1998, a break-even cost for a badger removal exercise was calculated to be £8,454 per km2. This figure may be under-estimated because it takes no account of any NHI’s prevented after 2012. The more limited reactive culls were found to have no significant impact. This applied to both the treated area and outer 2km ring. The data also showed that the culls only reduced confirmed TB with no significant impact on unconfirmed TB. This was also found by the ISG when they reported results in 2007. Arguments surrounding badger culling in the UK have been poorly based due to incomplete data. In view of this and media hype, it should be emphasised that after the first year of substantial culling across the study area, 9 years of data were needed to clearly see the full extent by which TB dropped in the RBCT. This has implications for the culls which started in South West England in 2013. If the current reporting delay of 20 months persists, it may be the autumn of 2023 at the earliest before the impact of these culls becomes clear. Also, if culls stop after year four in each zone, this risks benefits falling short of those achieved in the RBCT.

scholarly journals Randomised Badger Culling Trial: How big was the perturbation effect?

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Confidence Intervals ◽  
Bovine Tuberculosis ◽  
Statistical Error ◽  
Badger Culling ◽  
Uk Government ◽  
Surrounding Areas ◽  
The Uk ◽  
Perturbation Effect

In a report issued to the UK government in 2007 on the Randomised Badger Culling Trial (RBCT), it was stated that the incidence of bovine tuberculosis (TB) in cattle increased in areas surrounding where badgers were removed. It is known that badger culling perturbs badgers and this leads to increased TB transmission in and around these treated areas. The increase in TB in the surrounding areas was attributed to this process. In this study of the RBCT analysis it was found that large TB increases in areas surrounding proactively treated areas depended heavily on adjustments made for pre-cull history. This work looks at the basis for applying these adjustments. Since it is not possible to remove statistical error in the data, which confidence intervals suggest may have been large, it is argued that it was unsafe to apply these adjustments. As such it is argued that TB increases due to perturbation in the report presented to the UK government in 2007 may have been over-estimated.

scholarly journals Randomised Badger Culling Trial: How big was the perturbation effect?

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Confidence Intervals ◽  
Bovine Tuberculosis ◽  
Statistical Error ◽  
Badger Culling ◽  
Uk Government ◽  
Surrounding Areas ◽  
The Uk ◽  
Perturbation Effect

In a report issued to the UK government in 2007 on the Randomised Badger Culling Trial (RBCT), it was stated that the incidence of bovine tuberculosis (TB) in cattle increased in areas surrounding where badgers were removed. It is known that badger culling perturbs badgers and this leads to increased TB transmission in and around these treated areas. The increase in TB in the surrounding areas was attributed to this process. In this study of the RBCT analysis it was found that large TB increases in areas surrounding proactively treated areas depended heavily on adjustments made for pre-cull history. This work looks at the basis for applying these adjustments. Since it is not possible to remove statistical error in the data, which confidence intervals suggest may have been large, it is argued that it was unsafe to apply these adjustments. As such it is argued that TB increases due to perturbation in the report presented to the UK government in 2007 may have been over-estimated.

scholarly journals Doubts concerning the analysis of data collected in areas surrounding badger culled areas of the RBCT

2016 ◽  
Author(s):  
David Hendy
Keyword(s):  
Confidence Intervals ◽  
Bovine Tuberculosis ◽  
Statistical Error ◽  
Badger Culling ◽  
Uk Government ◽  
Surrounding Areas ◽  
The Uk

In a report issued to the UK government in 2007 on the Randomised Badger Culling Trial (RBCT), it was stated that the incidence of bovine tuberculosis (TB) in cattle increased in areas surrounding where badgers were removed. It is known that badger culling perturbs badgers and this leads to increased TB transmission in and around these treated areas. The increase in TB in the surrounding areas was attributed to this process. In this study of the RBCT analysis it was found that large TB increases in areas surrounding proactively treated areas depended heavily on adjustments made for pre-cull history. This work looks at the basis for applying these adjustments. Since it is not possible to remove statistical error in the data, which confidence intervals suggest may have been large, it is argued that it was unsafe to apply these adjustments. As such it is argued that TB increases due to perturbation in the report presented to the UK government in 2007 may have been grossly over-estimated.

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