Statistics in veterinary nursing research: what to know before starting the study
Abstract
The perspective that a finished study will return statistically significant results rests on the choice of an adequate sample size and statistical models to make the calculations. Unfortunately, it is not rare that the statistical input into experimental research is often not considered until the results have already been achieved. This is often discouraging since invalid conclusions are frequently taken due to inappropriate statistical preparation. This paper attempts to highlight this knowledge gap by describing some of the statistical considerations that are appropriate when designing a clinical or an epidemiological research study in veterinary nursing, with a keen focus on sample size calculation.
It is essential that veterinary nurses conducting research have a basic knowledge of statistics, thus being able to provide useful and solid analyses that can be read with confidence. Usually the statistical methods to be used are dependent on the study design; depending on the type of study design (as longitudinal or cross-sectional, prospective or retrospective, or matched or unmatched case-control), the statistical methods to be applied for the analysis of data might be different. Therefore, a very detailed plan of the study should be performed before the study starts (Kirkwood and Sterne, 2003).
An essential part of planning any research is to decide how many objects (i.e. animals, people, among others) are going to be studied. Choosing a suitable sample size is a crucial step that must be considered primarily, justifying that the study is capable of answering the question posed and is now a component of research proposals required by most funding agencies (Evans and O'Connor, 2007; Fosgate, 2009;Boyd et al, 2011; Pandis et al, 2011Ayeni et al, 2012). Sample sizes that are insuf-ficient cannot generate trustworthy answers to the research questions or hypotheses that need to be tested (Fitzner and Heckinger, 2010), while sample sizes that are too large can be a waste of time, money and resources, often raising ethical questions (Noordzij et al, 2011). As such, a suitable sample size uses time and resources in the most gainful manner and is vital to producing valuable research outcomes (Fitzner and Heckinger, 2010; Scott et al, 2011; Scott et al, 2012). Unfortunately, as frequently observed in systematic reviews and meta-analysis studies, sample size calculation is regularly based on assumptions that are recurrently inaccurate, and are inadequately stated and often flawed (Charles et al, 2009). Thus, this paper attempted to highlight this knowledge gap by describing some of the statistical considerations that are appropriate when designing a clinical or an epidemiological research study in veterinary nursing, with a keen focus on sample size calculation.
Register now to continue reading
Thank you for visiting The Veterinary Nurse and reading some of our peer-reviewed content for veterinary professionals. To continue reading this article, please register today.