Guidance

Calibration Weighting for the Farm Business Survey (FBS) in England – November 2025 update

Published 17 November 2025

Applies to England

© Crown copyright 2025

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This publication is available at https://www.gov.uk/government/publications/calibration-weighting-for-the-farm-business-survey-fbs-in-england-november-2025-update/calibration-weighting-for-the-farm-business-survey-fbs-in-england-november-2025-update

Outliers

An outlier is an observation that is significantly different from other observations within the dataset. Within some farm types, there are small sample sizes and a range of enterprises which means some individual farms can have a large influence on the results. These influential farms are treated as outliers and are given a weight of one as part of the weighting process so that they only represent themselves in the results.

Weighting

As the FBS is a sample survey, the sample data needs to be weighted to produce estimates of the FBS population which is made up of farm businesses that have a standard output of at least £21 thousand within the wider population of the June Business level dataset. The FBS population covers around 50% of all farm businesses in England whilst accounting for approximately 98% of the total standard output. Calibration weighting is used in the FBS to reduce the non response bias and improve precision, it is a two stage process:

  1. Initial weight, also known as the design weight, is the inverse sampling fraction (population / sample) of each stratum (farm type by farm size).
    For example, if there were 250 small cereal farms in the population and of these 50 were sampled for the FBS, then the initial weight for these 50 farms would be 5 (250/50).

  2. Calibration weights are then calculated, adjusting the initial weights via a calibration procedure. This produces correct population totals for a series of calibration variables (called constraints) for which accurate values within the FBS population are known from other sources. This ensures that the weights produce precise estimates of other variables, with little bias, despite the inevitable imperfections of the sampling strategy.

Due to the phasing out of the Direct Payments and the payments being delinked from 2024, some of the calibration data are no longer available and have had to be removed from the calibration model. These variables are:

  • Basic Payment Scheme moorland area
  • Severely Disadvantaged Area (SDA) that is not moorland
  • All non-SDA activated entitlement

These variables have been replaced by the area of grassland (permanent and temporary) and area of rough grazing which can be used as a proxy for SDA and non-SDA area.
The updated FBS constraints (all of which are England only), with new variables highlighted in bold, are as follows:

  • The number of farms in the population
  • The number of farms in the population by farm type
  • The number of farms in the population by farm size
  • Volume of milk produced
  • Area of Wheat
  • Area of Barley
  • Area of Oil Seed Rape
  • Area of grassland (permanent and temporary)
  • Area of rough grazing
  • Total Area
  • Full Agricultural Tenancy Area
  • Other Rented area (Farm Business Tenancy)
  • Number of Dairy Cows
  • Number of Beef Breed herd
  • Number of Breeding Ewes
  • Number of Breeding Pigs
  • Area organic or in conversion
  • Number of laying birds
  • Number of meat birds
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