Table 1

Testing the hypothesis that GC% values sampled from 20-kb windows follow a binomial distribution
seq
 # win (n)
 mean
 var σ2
 binomial var
σ2/
 c2 = (n - 1) σ2/
 p-value
MHC class III
 32
 0.5188
 0.0005345
 0.00001248
 42.8215
 1327.47
 0
MHC class II
 45
 0.4105
 0.0007268
 0.00001210
 60.0709
 2703.19
 0
random (class III)
 32
 0.5185
 0.00001137
 0.00001248
 0.9110
 28.2402
 0.609
random (class II)
 45
 0.4106
 0.00001255
 0.00001210
 1.0369
 45.6244
 0.404
B. burgdorferi
 45
 0.2859
 0.0001515
 0.00001021
 14.8432
 653.099
 0

Five sequences are tested: MHC class III and MHC class II isochore sequences, two random sequences similar these two MHC sequences (same length and same base composition), and bacterium Borrelia burgdorferi genome sequence. Detailed explanation of column headers: 1. Sequence name. 2. Total number of windows in the sequence (n), with each contributing a GC% value. 3. Mean of the GC% (m). 4. Variance of the GC% (σ2). 5. Variance of GC% expected from a binomial distribution ( = m(1 - m)/20000). 6. Ratio of the two variances σ2/ 7. test statistic c2 = (n - 1) σ2/. 8. p-value from the binomial distribution test.

Li et al. Genome Biology 2002 3:preprint0009.1   doi:10.1186/gb-2002-3-11-preprint0009