Fig. 7 The error rate performance of the proposed SIR scheme in Rayleigh fading and AWGN channels using different variance correction factors α=(0.5,1,1.5,2,2,5).
In all the simulations we keep the relay at S N R iR =1 dB to represent poor channel condition Fig. 8 The error rate performance of the proposed SIR scheme with assymtric setup in Rayleigh fading and AWGN channels using different variance correction factors α=(0.5,1,1.5,2,2,5).
Heterogeneity of variances was corrected using general least square (GLS) models including the 'varIdent' variance structure (different variance per factor level, this R-function is found in the 'nlme' package (Pinheiro et al. 2009).
To do this, we analyzed growth rate using mixed linear models that were able to fit different variances for random factors.
Hence, we can estimate the variance factors.
Likewise, species richness had no effect on biomass when included as first experimental factor in a GLS with different variances per fertilization level.
Current approaches employ (i) multivariate analysis on existing monitoring data to allocate variance to different stress factors [25] and (ii) extend triad-based approaches of relating local habitat conditions with chemical contamination and in situ effects detected as biomarkers in aquatic wildlife [26] and in caged fish.
The Eigenvalues for different factors, percentage variance accounted, cumulative percentage variance and component loadings (Varimax rotated) are given in Table 2.
Variance components are derived from statistical random effects models [ 8], by which the total variance in data is partitioned into estimated variance components associated with different random factors, i.e. sources of variability, in the model.
The separation of variances arising from different experimental factors and from the residual noise is achieved as follows.
