Michael Thrusfield*, Helen Brown

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract / Description of output

Information on disease and associated events, such as productivity, can be obtained from surveys. These involve counting members of an aggregate of units and measuring their characteristics. If all animals in a population are investigated then the survey is a census. The validity of sampling theory is based on the assumption that an aggregate of units can be divided into representative subâunits, and that characteristics of the aggregate can be estimated from the subâunits. There are two main types of sampling: nonâprobability sampling and probability sampling. The choosing of sample size depends on nonâstatistical and statistical considerations. Optimizing the number of herds and the number of animals selected in twoâstage sampling to demonstrate freedom from disease is an important consideration. The sampleâsize calculation, accommodating imperfect tests, is a twoâstage procedure, involving determination of the number of aggregates to be sampled, and the number of animals to be sampled in each aggregate.

Original languageEnglish
Title of host publicationVeterinary Epidemiology: Fourth Edition
Number of pages26
ISBN (Electronic)9781118280249
ISBN (Print)9781118280287
Publication statusPublished - 27 Nov 2017

Keywords / Materials (for Non-textual outputs)

  • Census
  • Imperfect tests
  • Non-probability sampling
  • Probability sampling
  • Sample optimization
  • Sample surveys
  • Sampling theory
  • Surveys


Dive into the research topics of 'Surveys'. Together they form a unique fingerprint.

Cite this