class Statsample::Anova::OneWayWithVectors

One Way Anova with vectors 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::OneWayWithVectors.new([v1,v2,v3])
anova.f
=> 0.0243902439024391
anova.probability
=> 0.975953044203438
anova.sst 
=> 32.9333333333333

One Way Anova with vectors 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::OneWayWithVectors.new([v1,v2,v3])
anova.f
=> 0.0243902439024391
anova.probability
=> 0.975953044203438
anova.sst 
=> 32.9333333333333

Attributes

contrasts[R]

Array with stored contrasts

summary_contrasts[RW]

Show on summary of contrasts

summary_descriptives[RW]

Show on summary descriptives for vectors

summary_levene[RW]

Show on summary Levene test

Public Class Methods

new(*args) click to toggle source

Calls superclass method Statsample::Anova::OneWay.new

# File lib/statsample/anova/oneway.rb, line 91
def initialize(*args)
  if args[0].is_a? Array
    @vectors=args.shift
  else
    @vectors=args.find_all {|v| v.is_a? Statsample::Vector}
    opts=args.find {|v| v.is_a? Hash}
  end
  opts||=Hash.new
  opts_default={:name=>_("Anova One-Way"), 
                :name_numerator=>_("Between Groups"),
                :name_denominator=>_("Within Groups"),
                :summary_descriptives=>false,
                :summary_levene=>true,
                :summary_contrasts=>true
  }
  @opts=opts_default.merge(opts).merge(:ss_num=>ssbg, :ss_den=>sswg, :df_num=>df_bg, :df_den=>df_wg)
  @contrasts=[]
  super(@opts)
end

Public Instance Methods

contrast(opts=Hash.new) click to toggle source

Generates and store a contrast. Options should be provided as a hash [:c]=>contrast vector [:c1 - :c2]=>index for automatic construction of contrast [:name]=>contrast name

# File lib/statsample/anova/oneway.rb, line 120
def contrast(opts=Hash.new)
  name=opts[:name] || _("Contrast for %s") % @name
  opts=opts.merge({:vectors=>@vectors, :name=>name})
  c=Statsample::Anova::Contrast.new(opts)
  @contrasts.push(c)
  c
end

df_bg() click to toggle source

Degrees of freedom between groups

# File lib/statsample/anova/oneway.rb, line 155
def df_bg
    k-1
end

df_wg() click to toggle source

Degrees of freedom within groups

# File lib/statsample/anova/oneway.rb, line 148
def df_wg
  @dk_wg||=n-k
end

k() click to toggle source

# File lib/statsample/anova/oneway.rb, line 151
def k
  @k||=@vectors.size
end

levene() click to toggle source

# File lib/statsample/anova/oneway.rb, line 128
def levene
  Statsample::Test.levene(@vectors, :name=>_("Test of Homogeneity of variances (Levene)"))
end

n() click to toggle source

Total number of cases

# File lib/statsample/anova/oneway.rb, line 159
def n
    @vectors.inject(0){|a,v| a+v.size}
end

ssbg() click to toggle source

Sum of squares between groups

# File lib/statsample/anova/oneway.rb, line 141
def ssbg
  m=total_mean
  @vectors.inject(0) do |total,vector|
    total + (vector.mean-m).square * vector.size 
  end
end

sswg() click to toggle source

Sum of squares within groups

# File lib/statsample/anova/oneway.rb, line 137
def sswg
  @sswg||=@vectors.inject(0) {|total,vector| total+vector.ss }
end

total_mean() click to toggle source

Total mean

# File lib/statsample/anova/oneway.rb, line 132
def total_mean
  sum=@vectors.inject(0){|a,v| a+v.sum}
  sum.quo(n)
end