Cargando…
Sample Size Estimation in Veterinary Epidemiologic Research
In the design of intervention and observational epidemiological studies sample size calculations are used to provide estimates of the minimum number of observations that need to be made to ensure that the stated objectives of a study are met. Justification of the number of subjects enrolled into a s...
Autor principal: | |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Frontiers Media S.A.
2021
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7925405/ https://www.ncbi.nlm.nih.gov/pubmed/33681313 http://dx.doi.org/10.3389/fvets.2020.539573 |
_version_ | 1783659264054657024 |
---|---|
author | Stevenson, Mark A. |
author_facet | Stevenson, Mark A. |
author_sort | Stevenson, Mark A. |
collection | PubMed |
description | In the design of intervention and observational epidemiological studies sample size calculations are used to provide estimates of the minimum number of observations that need to be made to ensure that the stated objectives of a study are met. Justification of the number of subjects enrolled into a study and details of the assumptions and methodologies used to derive sample size estimates are now a mandatory component of grant application processes by funding agencies. Studies with insufficient numbers of study subjects run the risk of failing to identify differences among treatment or exposure groups when differences do, in fact, exist. Selection of a number of study subjects greater than that actually required results in a wastage of time and resources. In contrast to human epidemiological research, individual study subjects in a veterinary setting are almost always aggregated into hierarchical groups and, for this reason, sample size estimates calculated using formulae that assume data independence are not appropriate. This paper provides an overview of the reasons researchers might need to calculate an appropriate sample size in veterinary epidemiology and a summary of sample size calculation methods. Two approaches are presented for dealing with lack of data independence when calculating sample sizes: (1) inflation of crude sample size estimates using a design effect; and (2) simulation-based methods. The advantage of simulation methods is that appropriate sample sizes can be estimated for complex study designs for which formula-based methods are not available. A description of the methodological approach for simulation is described and a worked example provided. |
format | Online Article Text |
id | pubmed-7925405 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Frontiers Media S.A. |
record_format | MEDLINE/PubMed |
spelling | pubmed-79254052021-03-04 Sample Size Estimation in Veterinary Epidemiologic Research Stevenson, Mark A. Front Vet Sci Veterinary Science In the design of intervention and observational epidemiological studies sample size calculations are used to provide estimates of the minimum number of observations that need to be made to ensure that the stated objectives of a study are met. Justification of the number of subjects enrolled into a study and details of the assumptions and methodologies used to derive sample size estimates are now a mandatory component of grant application processes by funding agencies. Studies with insufficient numbers of study subjects run the risk of failing to identify differences among treatment or exposure groups when differences do, in fact, exist. Selection of a number of study subjects greater than that actually required results in a wastage of time and resources. In contrast to human epidemiological research, individual study subjects in a veterinary setting are almost always aggregated into hierarchical groups and, for this reason, sample size estimates calculated using formulae that assume data independence are not appropriate. This paper provides an overview of the reasons researchers might need to calculate an appropriate sample size in veterinary epidemiology and a summary of sample size calculation methods. Two approaches are presented for dealing with lack of data independence when calculating sample sizes: (1) inflation of crude sample size estimates using a design effect; and (2) simulation-based methods. The advantage of simulation methods is that appropriate sample sizes can be estimated for complex study designs for which formula-based methods are not available. A description of the methodological approach for simulation is described and a worked example provided. Frontiers Media S.A. 2021-02-17 /pmc/articles/PMC7925405/ /pubmed/33681313 http://dx.doi.org/10.3389/fvets.2020.539573 Text en Copyright © 2021 Stevenson. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. |
spellingShingle | Veterinary Science Stevenson, Mark A. Sample Size Estimation in Veterinary Epidemiologic Research |
title | Sample Size Estimation in Veterinary Epidemiologic Research |
title_full | Sample Size Estimation in Veterinary Epidemiologic Research |
title_fullStr | Sample Size Estimation in Veterinary Epidemiologic Research |
title_full_unstemmed | Sample Size Estimation in Veterinary Epidemiologic Research |
title_short | Sample Size Estimation in Veterinary Epidemiologic Research |
title_sort | sample size estimation in veterinary epidemiologic research |
topic | Veterinary Science |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7925405/ https://www.ncbi.nlm.nih.gov/pubmed/33681313 http://dx.doi.org/10.3389/fvets.2020.539573 |
work_keys_str_mv | AT stevensonmarka samplesizeestimationinveterinaryepidemiologicresearch |