Published March 2004 | Version v1
Report

Update of GMA code to solve the PPP problem (technically)

  • 1. International Atomic Energy Agency, Nuclear Data Section, Vienna (Austria)

Description

The GMA code has been updated to introduce the Chiba-Smith option to address the problem of PPP (Peelle's Pertinent Puzzle/Paradox). To avoid confusion, we will refer to this code, and results obtained using it, as GMAP. This code revision was accomplished with a minimum of intervention to the original version of GMA in order to avoid introducing coding errors. The Chiba-Smith approach was implemented by means of simple renormalization of the experimental absolute errors (square roots of the variances) after reading them in from the input file. We refer to this option as a 'technical' solution to exclude PPP since it is based on the subjective assumption by Chiba and Smith that when experimenters quote absolute total errors these are calculated by multiplying a fractional error (comparable to percent error) by the measured value. Thus, it is supposed that it is the fractional error that actually reflects the accuracy that the experimenter intends to convey to the reader. The PPP problem is a consequence of discrepancies, i.e., the scatter observed for various presumably comparable data obtained by different experimenters that is frequently beyond the quoted errors. We have found that two distinct effects can lead to the presence of PPP in data evaluated by the least-squares method. One effect can be attributed to the different shapes of distinct strongly correlated data sets. We choose to label the PPP effect that results from these strong correlations as maxi-PPP. The second effect arises when there is a spread of data and absolute uncertainties are assigned. Two data points with the same percent uncertainty (same accuracy), but having different values, will then be weighted differently by the least-squares evaluation process. The lowest point will be assigned the heaviest weight since the weighting factor corresponds to the reciprocal square of the absolute error

Part of:
Summary report of the second research co-ordination meeting on improvement of the standard cross sections for light elements

Additional details

Publishing Information

Imprint Title
Summary report of the second research co-ordination meeting on improvement of the standard cross sections for light elements
Imprint Pagination
370 p.
Journal Page Range
p. 333-342
Report number
INDC(NDS)--453

Conference

Title
2. research co-ordination meeting on improvement of the standard cross sections for light elements
Dates
13-17 Oct 2003
Place
Gaithersburg, MD (United States)

INIS

Country of Publication
International Atomic Energy Agency (IAEA)
Country of Input or Organization
International Atomic Energy Agency (IAEA)
INIS RN
35095169
Subject category
S99: GENERAL AND MISCELLANEOUS;
Resource subtype / Literary indicator
Conference
Descriptors DEI
ACCURACY; CORRELATIONS; ERRORS; EVALUATION; G CODES; LEAST SQUARE FIT; RENORMALIZATION
Descriptors DEC
COMPUTER CODES; MATHEMATICAL SOLUTIONS; MAXIMUM-LIKELIHOOD FIT; NUMERICAL SOLUTION

Optional Information

Notes
Figs