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tokens: ; Kudoh Basu 2003 ; Wiebe Watson 2004 ; Falceta-Gonçalves et al. 2008 ; Hildebrand et al. 2009 ; Houde et al. 2009 ). Reduction of due to averaging effects is of great importance in our paper. Roughly speaking, two main averaging effects exist. First, averaging along the LOS can reduce . That is, if there is more than one independent turbulent eddy along the LOS, the measured value of will be reduced (see Myers Goodman 1991 ; Zweibel 1996 ; Houde et al. 2009 ). Second, averaging the polarization angle within the telescope beam can also reduce (see Heitsch et al. 2001 ; Wiebe Watson 2004 ; Falceta-Gonçalves et al. 2008 ; Houde et al. 2009 ). The averaging effects in general make the step from Equation ( 2 ) to Equation ( 3 ) inaccurate. In the presence of the averaging effects, the CF method tends to overestimate . In this paper, we focus on the averaging effect along the LOS and propose a simple method to compensate for the effect. Using three-dimensional direct magnetohydrodynamic (MHD) turbulence simulations, we test the proposed technique. In Section 2 , we describe our numerical method and explain in detail how averaging along the LOS makes the conventional CF method overestimate . At the end of Section 2 , we describe our new technique. In Section 3 , we present the results of our numerical simulations. In Section 4 , we discuss our findings and summarize. 2. NUMERICAL METHOD AND THEORETICAL CONSIDERATIONS 2.1. Numerical Code To obtain turbulence data, we solve the following compressible MHD equations in a periodic box of size using an essentially non-oscillatory scheme (see Cho Lazarian 2002 ): with ∇ · and an isothermal equation of state , where C s is the sound speed and ρ is density. Here, is the velocity, is the magnetic field, and is the driving force. We use 512 3 grid points. In our simulations, C s = 0.1, , and . In all simulations, the rms velocity v rms is between ∼0.7 and ∼0.8, and the sonic Mach number is . Since the Alfvén speed of the mean field () is 1, the Alfvén Mach number is , which means that the turbulence considered in this paper is sub-Alfvénic. 2.2. Forcing In this work, we drive turbulence in Fourier space and consider only solenoidal () forcing. We use ∼100 forcing components isotropically distributed in the range , where k is the wavenumber and k f varies from simulation to simulation (see Table 1 ). Therefore, the peak of energy injection occurs at . More detailed descriptions of forcing can be found in Yoo Cho ( 2014 ). Table 1 Simulations Notes. a Sonic Mach number. b Alfvén speed of mean magnetic field. c Driving wavenumber. d L los is the system size and L f is the driving scale. In our simulations, L los = 2 π and . Therefore, we have . 2.3. Theoretical Considerations: The Effects of Averaging along an LOS Our main concern is to investigate the effect of the driving scale on the CF method. For this purpose, we change the driving scale by changing the driving wavenumber k f . If the driving scale is L f ,