INTERNAL QUALITY CONTROL OF RADIOIMMUNOASSAYS: MONITORING OF ERROR

1979 ◽  
Vol 80 (3) ◽  
pp. 365-372 ◽  
Author(s):  
D. W. WILSON ◽  
K. GRIFFITHS ◽  
K. W. KEMP ◽  
A. B. J. NIX ◽  
R. J. ROWLANDS
Keyword(s):  
Quality Control ◽  
Mean Value ◽  
Vital Role ◽  
Small Sample ◽  
Internal Quality ◽  
Statistical Inferences ◽  
Assay Performance ◽  
Control Pool ◽  
Small Sample Sizes ◽  
Control Plasma

A cumulative sum technique has been specially designed to monitor the error between replicate determinations made on quality control plasma for consecutive batches of assays. This procedure has played a vital role in assessing assay performance. Special consideration has been given to small sample sizes (n = 2 or 3) which is generally the rule rather than the exception in many situations. This technique has been applied to numerous steroid radioimmunoassays and has ensured that both the mean value and the standard error of hormone levels of a quality control pool were under control. Data from routine assays of oestriol and testosterone in plasma from women are presented. Since this technique provides a sensitive measure of monitoring error, it assists the endocrinologist in elucidating statistical inferences which are a manifestation of assay performance.

scholarly journals Impact of small sample sizes on the internal quality control: statistical uncertainties in the determination of root mean square deviations with respect to the sample mean (RMSD) or to a target value (RMSTD)

2020 ◽  
Author(s):  
Christian Beier
Keyword(s):  
Quality Control ◽  
Root Mean Square ◽  
Small Sample ◽  
Control Measures ◽  
Internal Quality ◽  
Mean Square ◽  
Sample Sizes ◽  
Sample Mean ◽  
Small Sample Sizes

AbstractInsufficient statistics due to small considered sample sizes can cause distinct problems in internal quality control (IQC) approaches. This issue concerns most of the currently applied IQC concepts either directly (if a root-mean-square-deviation metric is evaluated) or indirectly (if the IQC concept facilitates a standard deviation that was self-evaluated based on a very limited number (n≤30) of control measures). In clinical chemistry a famous example for the latter case is the common implementation of the Westgard Sigma Rules approach.This study quantifies the statistical uncertainties in the determination of root mean square (total) deviations related to the sample mean (RMSD) or to a target value (RMSTD). It is clearly shown that RMS(T)D values based on small data sets with n<50 samples are accompanied by a significant statistical uncertainty that needs to be considered in adequate IQC limit definitions. Two mathematical models are derived to reliably estimate an optimal adaptation function to adjust IQC limits to short charts of control measures.This article provides the theoretical background for the novel IQC method “Statistical Monitoring by Adaptive RMSTD Tests” (SMART) intended to monitor limited available numbers of recent control measures (usually n<20). The study also addresses a general problem in specificity of an IQC resulting from too small sample sizes during the evaluation period of the applied in-control standard deviation.

scholarly journals Pandora: 4-D white matter bundle population-based atlases derived from diffusion MRI fiber tractography

2020 ◽  
Author(s):  
Colin B Hansen ◽  
Qi Yang ◽  
Ilwoo Lyu ◽  
Francois Rheault ◽  
Cailey Kerley ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Mri ◽  
State Of The Art ◽  
Population Based ◽  
Small Sample ◽  
Fiber Tractography ◽  
Statistical Inferences ◽  
Small Sample Sizes ◽  
The Brain ◽  
Brain Atlases

AbstractBrain atlases have proven to be valuable neuroscience tools for localizing regions of interest and performing statistical inferences on populations. Although many human brain atlases exist, most do not contain information about white matter structures, often neglecting them completely or labelling all white matter as a single homogenous substrate. While few white matter atlases do exist based on diffusion MRI fiber tractography, they are often limited to descriptions of white matter as spatially separate “regions” rather than as white matter “bundles” or fascicles, which are well-known to overlap throughout the brain. Additional limitations include small sample sizes, few white matter pathways, and the use of outdated diffusion models and techniques. Here, we present a new population-based collection of white matter atlases represented in both volumetric and surface coordinates in a standard space. These atlases are based on 2443 subjects, and include 216 white matter bundles derived from 6 different state-of-the-art tractography techniques. This atlas is freely available and will be a useful resource for parcellation and segmentation.

scholarly journals The Statistical Monitoring by Adaptive RMSTD Tests: an efficient, informative, and customizable method for the complete internal quality control intended for low-frequent sampling of control measures

2020 ◽  
Author(s):  
Christian Beier
Keyword(s):  
Quality Control ◽  
Control Method ◽  
Small Sample ◽  
Control Measures ◽  
Internal Quality ◽  
Small Data ◽  
Control Mechanisms ◽  
Data Set ◽  
Statistical Monitoring ◽  
Frequent Sampling

AbstractTwo control mechanisms are relevant to perform an internal quality assurance: a permissible limit LSMC applied to single measures of control samples and a retrospective statistical analysis to detect increased imprecision and baseline drifts. A common statistical metric is the root mean square (total) deviation (RMSD/RMSTD). To focus on recent changes under low-frequent sampling conditions, the monitored amount of retrospective data is usually very small. Unfortunately, the calculated RMSTD of a small data set with n<50 samples has a significant statistical uncertainty that needs to be considered in adequate limit definitions. In particular, the minimum reasonable limit LRMSTD(n), applied to the RMSTD of a series of n samples, decreases from LSMC (e.g., 2.33*standard_deviation+bias) for n=1 towards Ltrue_RMSTD for n→∞ (long-term statistics). Two mathematical approaches were derived to reliably estimate an optimal function to adjust LRMSTD(n) to small sample sizes.This knowledge led to the development of a new quality-control method: the Statistical Monitoring by Adaptive RMSTD Tests (SMART). SMART requires just one mandatory limit (either LSMC or Ltrue_RMSTD) per analyte. By definition of up to 7 possible alert levels, SMART can early recognize and evaluate both the significance of a single outlier and establishing critical trends or shifts in recent SMC data. SMART is intended to efficiently monitor and evaluate small amounts of control data.

Internal quality control: best practice

2013 ◽  
Vol 66 (12) ◽  
pp. 1027-1032 ◽  
Author(s):  
Helen Kinns ◽  
Sarah Pitkin ◽  
David Housley ◽  
Danielle B Freedman
Keyword(s):  
Quality Control ◽  
Error Detection ◽  
Best Practice ◽  
Internal Quality Control ◽  
Internal Quality ◽  
Assay Performance ◽  
Clinically Significant ◽  
Clinical Biochemistry Laboratory ◽  
Definition Of ◽  
Selection Of

There is a wide variation in laboratory practice with regard to implementation and review of internal quality control (IQC). A poor approach can lead to a spectrum of scenarios from validation of incorrect patient results to over investigation of falsely rejected analytical runs. This article will provide a practical approach for the routine clinical biochemistry laboratory to introduce an efficient quality control system that will optimise error detection and reduce the rate of false rejection. Each stage of the IQC system is considered, from selection of IQC material to selection of IQC rules, and finally the appropriate action to follow when a rejection signal has been obtained. The main objective of IQC is to ensure day-to-day consistency of an analytical process and thus help to determine whether patient results are reliable enough to be released. The required quality and assay performance varies between analytes as does the definition of a clinically significant error. Unfortunately many laboratories currently decide what is clinically significant at the troubleshooting stage. Assay-specific IQC systems will reduce the number of inappropriate sample-run rejections compared with the blanket use of one IQC rule. In practice, only three or four different IQC rules are required for the whole of the routine biochemistry repertoire as assays are assigned into groups based on performance. The tools to categorise performance and assign IQC rules based on that performance are presented. Although significant investment of time and education is required prior to implementation, laboratories have shown that such systems achieve considerable reductions in cost and labour.

scholarly journals Review of Clinical Trials on the Effects of Tai Chi Practice on Primary Hypertension: The Current State of Study Design and Quality Control

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Yuke Teng ◽  
Sha Yang ◽  
Yuan Chen ◽  
Yuyi Guo ◽  
Yushi Hu ◽  
...  
Keyword(s):  
Quality Control ◽  
Tai Chi ◽  
Clinical Symptoms ◽  
Small Sample ◽  
Primary Hypertension ◽  
Psychological Status ◽  
Cochrane Library ◽  
Design Standards ◽  
Tai Chi Exercise ◽  
Small Sample Sizes

The modulation of Tai Chi in physiological function and psychological status attracts sustaining attention. This paper collected original articles regarding the effects of Tai Chi practice on modulating primary hypertension from 7 electronic databases (PubMed, Excerpta Medica Database, Cochrane Library, Web of Science, Chinese Knowledge Resource Integrated Database, Wanfang Database, and China Science and Technology Journal Database) from their dates of origin to October 1st, 2020. A total of 45 articles were included. The literature analyses have shown that the benefits of Tai Chi practice for blood pressure management have been identified in all of the included 45 studies, and Tai Chi exercise has shown significant efficacy in improving hypertension clinical symptoms and quality of life, compared to the majority of control interventions, though there are also some methodological issues, including small sample sizes, lack of exact randomization methods and quality control criteria, and lack of specific standards used to measure the characteristics of Tai Chi practice. In the future, the inclusion of additional design standards, stricter quality controls, and evaluation measures for the features of Tai Chi practice is required in trials evaluating its effects on hypertension.

Measurements method of the audio recordings acoustic quality indicator prepared for registration and processing in the Unified Biometric System

2019 ◽  
pp. 40-46 ◽  
Author(s):  
V.V. Savchenko ◽  
A.V. Savchenko
Keyword(s):  
Quality Control ◽  
Small Sample Size ◽  
Personal Data ◽  
Digital Processing ◽  
Small Sample ◽  
Practical Implementation ◽  
Acoustic Measurements ◽  
Pitch Frequency ◽  
Wide Range ◽  
Automated Quality Control

We consider the task of automated quality control of sound recordings containing voice samples of individuals. It is shown that in this task the most acute is the small sample size. In order to overcome this problem, we propose the novel method of acoustic measurements based on relative stability of the pitch frequency within a voice sample of short duration. An example of its practical implementation using aninter-periodic accumulation of a speech signal is considered. An experimental study with specially developed software provides statistical estimates of the effectiveness of the proposed method in noisy environments. It is shown that this method rejects the audio recording as unsuitable for a voice biometric identification with a probability of 0,95 or more for a signal to noise ratio below 15 dB. The obtained results are intended for use in the development of new and modifying existing systems of collecting and automated quality control of biometric personal data. The article is intended for a wide range of specialists in the field of acoustic measurements and digital processing of speech signals, as well as for practitioners who organize the work of authorized organizations in preparing for registration samples of biometric personal data.

Sign in / Sign up

Export Citation Format

Share Document