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Information Technology Laboratory / Statistical Engineering Division

Gaithersburg Group

Projects/Programs

Displaying 1 - 25 of 27

Building Joint Sealant Service Life Prediction

Ongoing
The primary building sealant problem is that no method exists to provide high quality data for elucidating the relative importance of the k = 4 major weathering factors: X1: temperature, X2: humidity, X3: ultra-violet radiation, and X4: mechanical loading(and interactions) on the change in pre

Cement Characteristics by Direct Phase Assessment

Ongoing
DESCRIPTION: The major research goal is the accurate prediction of field performance metrics from accurate characterization of mineralogical composition and texture. Compounding characterization and prediction problems is the widespread reliance since the 1930's on the Bogue estimates of composition

Comparison of Internet Congestion-Control Algorithms

Completed
Complex systems are generically characterized by a large number of factors and a large number of potential responses, hence statistical questions immediately present themselves as to 1. What should be measured? 2. What experiment design should be used to generate content-full data? 3. How should

Computational Biology: Comparison of Cell Image Segmentation Algorithms

Ongoing
The Problem: The initial project problem was to determine whether image analysis techniques existed (or could be developed by the ITL groups) which would assist in the automatic differentiation of the A10 and 3T3 cell lines. The larger problem at hand was to determine what factors (and interactions)

Design and Analysis of Key Comparisons

Ongoing
DESCRIPTION: With the recent signing of the Mutual Recognition Arrangement (MRA), National Metrology Institutes (NMI's) and Regional Metrology Organizations (RMO's) around the world have committed themselves to establishing the equivalence of their measurement standards. Currently, however, there is

Detecting Change Points in Surface Temperature Records

Ongoing
DESCRIPTION: For the purpose of exposition, consider the record daily minimums averaged by month for a station near Reno Nevada. There is a clear drop in the level between 1920 and 1940 and a positive drift starting at about 1980. There is also however, considerable variability due to seasonal

e-Statistics

Ongoing
DESCRIPTION: e-FITS is a web-based tool, currently available to NIST staff, used to perform the following tasks for over 100 probability distributions. Generate graphs of probability functions (probability density, cumulative distribution, inverse cumulative distribution, hazard, cumulative hazard

Experimental Evaluation of Large-Scale Parallel Measurement Systems

Ongoing
DESCRIPTION: An archetype among biological experiments is gene-by-gene determination of the expression difference between two groups of biological units. For each gene, the experiment yields a data set consisting of one or more expression values for each unit. Gene to gene, these data sets can be
Figure4

Functional Analysis of Variance

Ongoing
Assessment of measurement data often raises statistical inference questions which have not been adequately addressed in the statistical literature. For example, NIST scientists may encounter issues on whether two measurement techniques give arise to similar measurement curves, whether there is a

metRology for Microsoft Excel

Ongoing
DESCRIPTION: The current version of the metRology for Microsoft Excel add-in focuses on uncertainty analysis using the methods outlined in the JCGM Guide the Expression of Uncertainty in Measurement (often referred to as the GUM). These methods for uncertainty analysis are widely accepted and their

metRology Software Project

Ongoing
DESCRIPTION: The current version of the metRology package focuses on statistical functions for uncertainty analysis and for the analysis of interlaboratory studies and key comparisons. A number of the functions focus on uncertainty analysis using the methods outlined in the JCGM Guide to the

NIST/SEMATECH Engineering Statistics Handbook

Ongoing
Description: The project began with a request from SEMATECH, a consortium of major U.S. semiconductor manufacturers, to update the National Bureau of Standards (NBS) Handbook 91, Experimental Statistics. Handbook 91, written by Mary Natrella of the NBS Statistical Engineering Lab, was a best-selling
Hawkes intensities and QQ plots for MLE fits for several stairs

A Point Process Model for Evacuation Flows: The Hawkes Mode

Ongoing
Results from a case study of evacuations of 14 office and residential buildings in the United States led us to model occupant exit times as a Hawkes point process, N(t). N(t) the number of evacuee exits in the time interval (0,t]. Because the Hawkes model is self-similar, human to human interaction

Quantifying Uncertainty in Accelerometer Sensitivity Studies

Ongoing
DESCRIPTION: International Key Comparisons are performed. The key comparison reference value for charge sensitivity as a function of frequency and the accompanying uncertainty are the principal objectives of these studies. In a suggested mixed effects model several methods for evaluation of this
Staff from the Department of Homeland Security participate in a hands-on exercise as part of the SED short course on experiment design.

Short Courses

Ongoing
Staff members of the Statistical Engineering Division regularly offer short courses on uncertainty analysis, design of experiments, and other topics in statistical metrology at NIST, at conferences open to the public, and at other government agencies. Prospective attendees of short courses at NIST
DataPlotRelativeErrorBoxplot2

Statistical Methods for Quantitative Imaging

Ongoing
In this project, we have gained valuable experience in the emerging area of developing metrology support for medical image decision making, and we have focused mainly in the area of high resolution CT imaging for lung nodules,using both phantoms and clinical data, in the context of RSNA's QIBA

Statistical Process Monitoring for Autocorrelated Data

Ongoing
DESCRIPTION: Process monitoring is very important for industries. Statistical methodologies have been used to monitor various production process successfully. The majority of statistical process monitoring techniques assume that the process data are free of autocorreation. However, this assumption
Splicing Multiple SRM Correction Factor

Statistical Support for Bioassay Standard Development

Ongoing
Biological assays are procedures that can determine concentration, purity, or biological activity of a substance through scientific experimentation. Fluorescence-based quantification one of the most widely used technique in quantitative clinical and biochemical assays, and it depends on the

Statistics for Ballistics Identification

Ongoing
DESCRIPTION: Statistical Engineering Division has had an ongoing collaboration with NIST's Precision Engineering Division (now Semiconductor and Dimensional Metrology Division) and Office of Law Enforcement Standards (now in the Office of Special Programs) in the field of firearms and tool mark

Statistics for Food and Supplement SRMs

Ongoing
DESCRIPTION: NIST's program of food and reference materials with reliable content values for various nutrients helps the food industry comply with FDA rules and helps consumers in making dietary choices. The Nutrition Labeling and Education Act of 1990 requires that labels on processed foods

Tunable Compression of Wind Tunnel Data

Ongoing
Variability of Bending Moments The values of the bending moments vary both within each run, and between runs. The between-runs variability provides a standard against which one should assess the severity of any loss of information that a data compression scheme may incur. To assess it, we fitted a

Uncertainty analysis for autocorrelated measurement data

Ongoing
DESCRIPTION: When repeated measurements are autocorrelated, it is not appropriate to use the traditional approach to calculate the uncertainty of the average of the measurements, which assumes that the measurements are statistically independent. We need to develop approaches for assessing