Methodology for an Operationally-Based Test Length Decision

1997 ◽  
Author(s):  
Donald P. Gaver ◽  
Patricia A. Jacobs
Keyword(s):  
Test Length

scholarly journals The influence of edge effects on crack propagation in snow stability tests

2014 ◽  
Vol 8 (1) ◽  
pp. 229-257
Author(s):  
E. H. Bair ◽  
R. Simenhois ◽  
A. van Herwijnen ◽  
K. Birkeland
Keyword(s):  
Crack Propagation ◽  
Strain Energy ◽  
Wave Speed ◽  
Strain Energy Release Rate ◽  
Field Tests ◽  
Strain Energy Release ◽  
Element Model ◽  
Fe Model ◽  
Test Length ◽  
Column Tests

Abstract. Propagation tests are used to assess the likelihood of crack propagation in a snowpack, yet little is known about how test length affects propagation. Guidelines suggest beams with lengths around 1 m for Extended Column Tests (ECTs) and Propagation Saw Tests (PSTs). To examine how test length affects propagation, we performed 163 ECTs and PSTs 1 to 10 m long. On days with full crack propagation in 1.0 to 1.5 m tests, we then made videos of tests 2 to 10 m long. We inserted markers for particle tracking to measure collapse amplitude, collapse wave speed, and wavelength. We also used a finite element model to simulate the strain energy release rate at fixed crack lengths. We find that: (1) the proportion of tests with full propagation decreased with test length; (2) collapse was greater at the ends of the beams than in the centers; (3) collapse amplitudes in the longer tests were consistent with the shorter tests and did not reach a constant value; (4) collapse wavelengths in the longer tests were around 3 m, 2 × greater than what is predicted by the anticrack model. Based on our field tests and FE models, we conclude that the shorter tests fully propagated more frequently because of increased stress concentration from the far edge. The FE model suggests this edge effect occurs for PSTs up to 2 m long or a crack to beam length ratio ≥ 0.20. Our results suggest that ECT and PST length guidelines may need to be revisited.

scholarly journals The Impact of Item Calibration Error on Variable-Length Cognitive Diagnostic Computerized Adaptive Testing

2020 ◽  
Vol 11 ◽  
Author(s):  
Xiaojian Sun ◽  
Yanlou Liu ◽  
Tao Xin ◽  
Naiqing Song
Keyword(s):  
Adverse Effects ◽  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Adaptive Testing ◽  
Unified Model ◽  
Variable Length ◽  
Calibration Error ◽  
Test Length ◽  
Test Efficiency ◽  
Item Parameters

Calibration errors are inevitable and should not be ignored during the estimation of item parameters. Items with calibration error can affect the measurement results of tests. One of the purposes of the current study is to investigate the impacts of the calibration errors during the estimation of item parameters on the measurement accuracy, average test length, and test efficiency for variable-length cognitive diagnostic computerized adaptive testing. The other purpose is to examine the methods for reducing the adverse effects of calibration errors. Simulation results show that (1) calibration error has negative effect on the measurement accuracy for the deterministic input, noisy “and” gate (DINA) model, and the reduced reparameterized unified model; (2) the average test lengths is shorter, and the test efficiency is overestimated for items with calibration errors; (3) the compensatory reparameterized unified model (CRUM) is less affected by the calibration errors, and the classification accuracy, average test length, and test efficiency are slightly stable in the CRUM framework; (4) methods such as improving the quality of items, using large calibration sample to calibrate the parameters of items, as well as using cross-validation method can reduce the adverse effects of calibration errors on CD-CAT.

A Note on the Length and Passing Score of a Mastery Test

1976 ◽  
Vol 1 (4) ◽  
pp. 359-364 ◽  
Author(s):  
Rand R. Wilcox
Keyword(s):  
Selection Procedure ◽  
Ranking And Selection ◽  
Test Length ◽  
Indifference Zone ◽  
Search Routine ◽  
Passing Score

Using an indifference zone formulation, Fhanér has described a ranking and selection procedure for determining the appropriate length of a mastery test. The purpose of this note is to relate Fhanér’s solution to one given by Millman, to give a criterion for the choice of a passing score, and to describe a search routine which will always yield the appropriate test length and implied passing score.

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