Sample Size Calculator For Agreement Studies

Let`s go back to the frequently asked questions about the design and analysis of measurement studies. 5. Bland JM, DG Altman. Correct statistics: analyses of measurement studies. Ultrasons Obst Gyn 2003;22:85-93. A table shows the sample size required for different Type I and Type II error levels. Hahn and Meeker [18] defined a tolerance interval that is an interval that can be indicated for at least a certain proportion, p, the population with some degree of confidence, 100 (1-α)%, and provided the sample estimates of the tolerance interval. We can see that their estimate of sample size is based on desired accuracy, without taking into account Type II (β) or performance errors, and only addresses the frequently asked question “How big is a sample needed to achieve a confidence interval?” Although our OLA confidence interval is similar to their tolerance range, theories and methods for estimating sample size are totally different. Our method of estimating sample size is derived not only from predetermined α, but also from the β. For μ-0, the calculation of the sample size can be written as follows: 13. Julious SA. Sample size for clinical trials with normal data.

Stat Med 2004;23:1921-1986. 7. Hamilton C, Stamey J. With Bland-Altman to evaluate the agreement between two medical devices – don`t forget the confidence intervals! J Clin Monit Comput 2007;21:331-333. To demonstrate that two methods are consistent, it is necessary to define an appropriate sample size in order to have a high probability (power) that the S- is located outside the 95 CI of the boundaries of the agreement. 17. Lin SC, Whipple DM, Ho CS. Assessing statistical equivalence using match limits and calculating the sample size associated with it. Common Stat Theor Methods 1998;27:1419-1432. Two methods are considered consensual when a pre-defined maximum allowable difference is greater than the upper agreement limit and below the lower limit of the contract. It is important to be aware of the clinically acceptable contractual limits set in advance. As with clinical studies of equivalence or non-inferiority, clinical agreement limits must be set in advance by clinical researchers and biostatistics.

Defining these matching limits can be a difficult aspect of the design of comparative studies, as they depend not only on the clinical scenario, but also on other variables. Nevertheless, we must try to define them; a Delphi survey (expert opinion) can be used for the design of the study. This survey is a group facilitation technique, which is a multi-step iterative process designed to transform an opinion into a group consensus [16]. The original article by Bland and Altman [1], which proposed the method of analysis of the agreement, received more than 30,000 citations in the biomedical literature and has increased in recent years.