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Surveillance Plan Template: Sampling Plan - Sample Size

This is a view of the template showing the suggested content of the Sampling Plan - Sample Size section of an Outbreak Surveillance Plan. Instructions are in green and should be deleted from the final draft.


Number of Premises to Sample

Control Area

[Example narrative]
In the Infected Zone, no distinction is made between premises as to which ones are ‘high-risk’, ‘medium-risk’, or ‘low-risk’ for exposure to [insert disease agent]. Consequently, all premises (census) in this zone will be sampled. All monitored premises MUST be sampled again prior to animal and animal product movement to meet permit requirements. When not moving animals or animal products, monitored premises are treated the same as at-risk premises (relaxed testing requirements). According to [insert data sources] information, the Infected Zone contains the following premises: [list each species with the number of premises in parentheses]. These initial numbers will likely change with the addition of local information such as [insert data sources] and surveillance team reports.

In the Buffer Zone, no distinction is made between contact and suspect premises that are ‘high risk’, ‘medium risk’, or ‘low risk’ for exposure to [insert disease agent]. Consequently, all contact and suspect premises (census) within this zone will be sampled. However, regarding at-risk and monitored premises in this zone, enough premises must be sampled to produce a 95% certainty (confidence) that at least one positive premises will be detected in the sample population, if at least 1-2% of the at-risk and monitored premises in the Buffer Zone have [insert species] shedding [insert disease agent] at the time of sampling. The estimated minimum number of at-risk and monitored premises to sample in the Buffer Zone is presented in Table [insert number]. All monitored premises MUST be sampled again prior to animal and animal product movement to meet permit requirements. When not moving animals or animal products, monitored premises are treated the same as at-risk premises (relaxed testing requirements).

 Table [insert number]. Minimum number of at-risk and monitored premises to sample in the Buffer Zone. The premises sample size assumes a sampling protocol with 95% confidence of detecting at least one infected premises if the inter-herd prevalence of [insert disease agent] is at least 1-2% inter-herd.

  

Minimum number of premises to sample with:

Total number of at-risk and monitored premises in Buffer Zone

1% inter-herd prevalence rate

2% inter-herd prevalence rate

[insert number] or less 

 Sample all premises

 Sample all premises

[insert number or delete row]

 [insert number or delete row]

 [insert number or delete row]

[insert number or delete row]

 [insert number or delete row]

   [insert number or delete row]

[insert number] or greater]

 [insert number]

 [insert number]

Surveillance Zone and Free Area

The goal of surveillance in the Surveillance Zone and the Free Zone is to detect disease incursions/threats to the Free Area for [insert disease agent]. No distinction is made between suspect premises that are 'high risk', medium risk', or 'low risk' for exposure to [insert disease agent]. Consequently, all suspect premises (census) within the Surveillance Zone will be sampled. However, regarding free premises, enough premises must be sampled to rpoduce a 95% certainty (confidence) that at least one positive premises will be detected in the sample population, is at least 1-2% of the premises in the Surveillance Zone and Free Area have [insert species] shedding [insert disease agent] at the time of sampling. The estimated minimum number of premises to sample is presented in Table [insert number].

Table [insert number]. Minimum number of premises to sample in the Surveillance Zone and Free Area. The premises sample size assumes a sampling protocol with 95% confidence of detecting at least one infected premises if the inter-herd prevalence of [insert disease agent] is at least 1-2%.

      

Minimum number of premises to sample with:

Total number of premises in SZ

1% inter-herd prevalence rate

2% inter-herd prevalence rate

[insert number] or less 

 Sample all premises

 Sample all premises

[insert number or delete row]

 [insert number or delete row]

 [insert number or delete row]

[insert number or delete row] 

 [insert number or delete row]

  [insert number or delete row]

 [insert number] or greater

 [insert number]

  [insert number]

 

Number of Individuals to Sample per Premises

Control Area ( Infected Zone and Buffer Zone) and Free Area (includes Surveillance Zone)

The minimum number of [insert species] to sample on each premises is given in Table [insert number] below. These calculations reflect the sample size required to be 95% confident or certain of including at least one positive [insert species] if [insert disease] is present at 5% prevalence with [insert %] sensitivity using [insert name of test e.g. PCR].

Table [insert number]. Number of [insert species] to sample on each premises.

Table [insert number]. Number of [insert species] to sample on each premises.

 

 

Number of [insert species] on the Premises

Minimum Number of [insert species] to Sample

[insert number] or less

Sample all individuals

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number or delete row]

[insert number] or greater

[insert number]

 

[Optional]List of the Premises and Animals to Actually Sample to Meet Sample Size Requirements

Premises

[Example narrative]
All premises in the Infected Zone within the Control Area, will be sampled, i.e. a census will be conducted. Consequently, it is not necessary to use a sampling method (e.g. simple random sampling or interval sampling) to identify a sub-sample of individual premises to visit and sample apart from the current inventory of premises. There are [insert number] premises that must be sampled in the Infected Zone.

All contact and suspect premises in the Buffer Zone within the Control Area will be sampled, i.e. a census will be conducted. Consequently, it is not necessary to use a sampling method (e.g. simple random sampling or interval sampling) to identify a sub-sample of premises to visit and sample apart from the current inventory of premises. There are [insert number] suspect premises that must be sampled in the Buffer Zone.

A sub-sample of at-risk and monitored premises in the Buffer Zone within the Control Area will be sampled. There are [insert number] at-risk and monitored premises in the Buffer Zone available to sample. [insert sampling method, e.g. simple random sampling or interval sampling] was used to identify the sub-sample of actual premises to visit and sample to meet the sample size requirement from among the [insert number] at-risk and monitored premises in the Buffer Zone. Table [insert number] lists the premises that should be initially visited and sampled. All monitored premises MUST be sampled again prior to animal and animal product movement to meet permit requirements. When not moving animals or animal products, monitored premises are treated the same as at-risk premises (relaxed testing requirements). [Note: the outbreak surveillance toolbox contains a “simple random sample” calculator and an “interval sampling” calculator to actually choose the unique premises to sample; the results could be listed in an accompanying Table]

All suspect premises in the Surveillance Zone will be sampled, i.e. a census will be conducted. Consequently, it is not necessary to use a sampling method (e.g. simple random sampling or interval sampling) to identify a sub-sample of premises to visit and smaple apart from the current inventory of premises. There are [insert number] suspect premises that must be sampled in the Surveillance Zone.

A sub-sample of premises in the Surveillance Zone and Free Area will be sampled. There are [insert number] premises in the Surveillance Zone and [insert number] premises in the Free Area that are available to sample. [insert sampling method, e.g. simple random sampling or interval sampling or some other sampling method] was used to identify the sub-sample of actual premises to visit and sample to meet the sample size requirement. Tables [insert numbers] lists the premises in the Surveillance Zone and Free Area, respectively, that should be initially visited and their animals sampled. [Note: the outbreak surveillance toolbox contains a “simple random sample” calculator and an “interval sampling” calculator to actually choose the unique premises to sample; the results could be listed in an accompanying Table]

Animals

[Example narrative]
[insert sampling method, e.g. simple random sampling or interval sampling or some other sampling method] was used to identify the sub-sample of actual animals to sample on previously identified premises to meet the sample size requirement in each of the following Areas/Zones. [Note: the outbreak surveillance toolbox contains a “simple random sample” calculator and an “interval sampling” calculator to actually choose the unique animals to sample from each premises; the results could be listed in an accompanying Table]

Tables [insert numbers] lists the animals matched to the aforementioned premises number that that should be initially sampled in the Infected Zone and Buffer Zone within the Control Area.

Tables [insert numbers] lists the animals matched to the aforementioned premises number that that should be initially sampled in the Surveillance Zone.

Tables [insert numbers] lists the animals matched to the aforementioned premises number that that should be initially sampled in the Free Area.

[insert the appropriate tables here]


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