Accession Number : ADA186711

Title :   Error Modeling and Confidence Interval Estimation for Inductively Coupled Plasma Calibration Curves.

Descriptive Note : Journal article Aug 86-Aug 87,

Corporate Author : NORTH CAROLINA UNIV AT CHAPEL HILL INST OF STATISTICS

Personal Author(s) : Watters, Robert L , Jr ; Carroll, Raymond J ; Spiegelman, Clifford H

PDF Url : ADA186711

Report Date : Feb 1987

Pagination or Media Count : 29

Abstract : A simple linear calibration function can be used over a wide concentration range for the Inductively Coupled Plasma (ICP) spectrometer due to its linear responses. The random errors over wide concentration ranges are not constant, and constant variance regression should not be used to estimate the calibration function. Weighted regression techniques are appropriate if the proper weights can be obtained. Use of the calibration curve to estimate. The concentration of one or more unknown samples is straightforward, but confidence interval estimation for multiple use of the calibration curve is les obvious. A method is described for modeling the error along the ICP calibration curve using the estimated parameters from the fitted model to calculate weights for the calibration curve fit. Multiple and single-use confidence interval estimates are obtained and results along the calibration curve are compared.

Descriptors :   *PLASMAS(PHYSICS), *SPECTROMETERS, CALIBRATION, CURVED PROFILES, REGRESSION ANALYSIS, VARIATIONS, COUPLING(INTERACTION), LINEAR SYSTEMS, ESTIMATES, ERRORS, MODELS, WEIGHTING FUNCTIONS, REGRESSION ANALYSIS

Subject Categories : Plasma Physics and Magnetohydrodynamics
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE