Concerns about a variance approach to the X-ray diffractometric estimation of microfibril angle in wood

Abstract

In this paper we raise three technical concerns about Evans’s 1999 Appita Journal “variance approach” to estimating microfibril angle. The first concern is associated with the approximation of the variance of an X-ray intensity half-profile by a function of the microfibril angle and the natural variability of the microfibril angle, S² ≈ μ²/2 + σ². The second concern is associated with the approximation of the natural variability of the microfibril angle by a function of the microfibril angle, σ² ≈ f(μ). 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 microfibril angle 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.

Citation

Verrill, Steve P.; Kretschmann, David E.; Herian, Victoria L.; Wiemann, Michael; Alden, Harry A. 2010. Concerns about a variance approach to the X-ray diffractometric estimation of microfibril angle in wood. Research Paper FPL-RP-658. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, 2010: [92] p.