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Contents
module Statsample
module Anova
# One Way Anova
# Example:
# v1=[2,3,4,5,6].to_scale
# v2=[3,3,4,5,6].to_scale
# v3=[5,3,1,5,6].to_scale
# anova=Statsample::Anova::OneWay.new([v1,v2,v3])
# anova.f
# => 0.0243902439024391
# anova.significance
# => 0.975953044203438
# anova.sst
# => 32.9333333333333
#
class OneWay
def initialize(vectors)
@vectors=vectors
end
# Total sum
def sum
@vectors.inject(0){|a,v| a+v.sum}
end
# Total mean
def mean
sum.quo(n)
end
# Total sum of squares
def sst
m=mean.to_f
@vectors.inject(0) {|total,vector| total+vector.sum_of_squares(m) }
end
# Sum of squares within groups
def sswg
@vectors.inject(0) {|total,vector| total+vector.sum_of_squares }
end
# Sum of squares between groups
def ssbg
m=mean
@vectors.inject(0) do |total,vector|
total + (vector.mean-m).square * vector.size
end
end
# Degrees of freedom within groups
def df_wg
@vectors.inject(0) {|a,v| a+(v.size-1)}
end
# Degrees of freedom between groups
def df_bg
@vectors.size-1
end
# Total Degrees of freedom
def df_total
n-1
end
# Total number of cases
def n
@vectors.inject(0){|a,v| a+v.size}
end
# Fisher
def f
k=@vectors.size
(ssbg*(n-k)) / (sswg*(k-1))
end
# Significance of Fisher
def significance
1.0-Distribution::F.cdf(f,df_bg,df_wg)
end
end
end
end
Version data entries
11 entries across 11 versions & 1 rubygems