Sample size calculations for skewed distributions
نویسندگان
چکیده
منابع مشابه
Sample size calculations for skewed distributions
BACKGROUND Sample size calculations should correspond to the intended method of analysis. Nevertheless, for non-normal distributions, they are often done on the basis of normal approximations, even when the data are to be analysed using generalized linear models (GLMs). METHODS For the case of comparison of two means, we use GLM theory to derive sample size formulae, with particular cases bei...
متن کاملInterval estimators for the population mean for skewed distributions with a small sample size
1 Interval estimators for the population mean for skewed distributions with a small sample size SUMMARY In nite population sampling it has long been known that for small sample sizes, when sampling from a skewed population, the usual frequentist intervals for the population mean cover the true value less often than their stated frequency of coverage. Recently a noninformative Bayesian approach ...
متن کاملSample-Size Calculations for Cohen's Kappa
In recent years, researchers in the psychosocial and biomedical sciences have become increasingly aware of the importance of sample-size calculations in the design of research projects. Such considerations are, however, rarely applied for studies involving agreement of raters. Published results on this topic are limited and generally provide rather complex formulas. In addition, they generally ...
متن کاملSample size calculations for randomized controlled trials.
Most informed consent documents for randomized controlled trials implicitly or explicitly promise the prospective participant that the trial has a reasonable chance of answering a medically important question. The medical literature, however, is replete with descriptions of trials that provided equivocal answers to the questions they addressed. Papers describing the results of such studies may ...
متن کاملSample size calculations based on a difference in medians for positively skewed outcomes in health care studies
BACKGROUND In healthcare research, outcomes with skewed probability distributions are common. Sample size calculations for such outcomes are typically based on estimates on a transformed scale (e.g. log) which may sometimes be difficult to obtain. In contrast, estimates of median and variance on the untransformed scale are generally easier to pre-specify. The aim of this paper is to describe ho...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: BMC Medical Research Methodology
سال: 2015
ISSN: 1471-2288
DOI: 10.1186/s12874-015-0023-0