Concerns About a Variance Approach to X-Ray Diffractometric Estimation of Microfibril Angle in Wood
Keywords:Microfibril angle estimation, bias, variance approach, cell rotation, cell tilt, cell cross-section, X-ray diffraction
AbstractIn this article, we raise three technical concerns about Evans' 1999 Appita Journal "variance approach" to estimating microfibril angle (MFA). The first concern is associated with the approximation of the variance of an X-ray intensity half-profile by a function of the MFA and the natural variability of the MFA. The second concern is associated with the approximation of the natural variability of the MFA by a function of the MFA. The third concern is associated with the fact that the variance approach was not designed to handle tilt in the fiber orientation. All three concerns are associated with potential biases in MFA estimates. We raise these three concerns so that other researchers interested in understanding, implementing, or extending the variance approach or in comparing the approach to other methods of estimating MFA will be aware of them.
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