The ADHD Combined group had the lowest explained variance of all groups on the spatial measures.
The data for PIR was analyzed using analysis of variance in a group balanced block design (Gomez and Gomez, 1984) and the means were compared by least significant difference (Steel and Torrie, 1982).
Traditional DE analysis aims to identify genes with significant changes in mean expression level between diseased and non-diseased samples, whereas DV analysis aims to identify genes with a significant change in variance of expression between a group of diseased patients and non-diseased individuals (see Fig. 1 for a comparison of DE, DC and DV patterns).
Even though the variance of the relatedness of a group of individuals declines with increasing number of loci (Queller and Goodnight 1989) the correlation between pedigree relatedness and pairwise relatedness estimates did not exceed 0.86 even when relatedness estimates were based on 771 single-nucleotide polymorphisms (SNPs; Santure et al. 2010).
Variables with repeated measures were analysed using the two-way repeated measures analysis of variance (ANOVA) fitting a group and time effect and a group by time interaction to ascertain if the two groups responded differently over time.
The linear mixed model (2) can be extended to divide phenotypic variance into estimates of the genetic and environmental variance containing information from genotypes of a group of N SNPs spanning a region.
For statistical comparisons of two samples, an unpaired, a two-tailed Student's t-test with distinction of equal and unequal variances in a group (Levene's test) was used to determine the significance of differences between means.
If the observed difference between the two groups was significantly large compared with the variance of a particular variable, then the groups were deemed incomparable for that variable.
The variance-fold is defined as the quotient of the variance of one group (for example, OA patients) and the variance of another group (for example, RA patients).
Although this third component is akin to indices of reproductive skew (Sherman et al. 1995; Nonacs 2000), such indices can be used more broadly to represent variance in resource distribution among members of a group or population (Kokko et al. 1999), while here we emphasize the fraction of a group's constituents that can be classified as non-reproductive helpers.
