Chi Squared Distribution Table

This class holds the distribution table for the Chi Squared distribution.

Class methods

alpha values

It returns the alpha values that are represented in the chi squared distribution table:

irb(main):001> RubyStatistics::Distribution::Tables::ChiSquared.alpha_values
=> [0.995, 0.99, 0.975, 0.95, 0.9, 0.1, 0.05, 0.025, 0.01, 0.005]

valid alpha?

It returns true if the specified alpha value is within the list of alpha values that are represented in the chi squared distribution table:

irb(main):002> RubyStatistics::Distribution::Tables::ChiSquared.valid_alpha?(0.1)
=> true
irb(main):003> RubyStatistics::Distribution::Tables::ChiSquared.valid_alpha?(0.2)
=> false

Alpha column

It returns the critical values and its degrees of freedom for the specified alpha value that is represented in the chi square distribution table. If the value is not known, it raises an error.

irb(main):004> RubyStatistics::Distribution::Tables::ChiSquared.alpha_column(0.02)
lib/ruby-statistics/distribution/tables/chi_squared.rb:76:in `alpha_column': Undefined alpha value. (RuntimeError)
	from (irb):4:in `<main>'
	from <internal:kernel>:187:in `loop'
	from bin/console:14:in `<main>'
irb(main):005> RubyStatistics::Distribution::Tables::ChiSquared.alpha_column(0.01)
=> 
[{:df=>1, :critical_value=>6.635},
 {:df=>2, :critical_value=>9.21},
 {:df=>3, :critical_value=>11.345},
 {:df=>4, :critical_value=>13.277},
 {:df=>5, :critical_value=>15.086},
 {:df=>6, :critical_value=>16.812},
 {:df=>7, :critical_value=>18.475},
 {:df=>8, :critical_value=>20.09},
 {:df=>9, :critical_value=>21.666},
 {:df=>10, :critical_value=>23.209},
 {:df=>11, :critical_value=>24.725},
 {:df=>12, :critical_value=>26.217},
 {:df=>13, :critical_value=>27.688},
 {:df=>14, :critical_value=>29.141},
 {:df=>15, :critical_value=>30.578},
 {:df=>16, :critical_value=>32.0},
 {:df=>17, :critical_value=>33.409},
 {:df=>18, :critical_value=>34.805},
 {:df=>19, :critical_value=>36.191},
 {:df=>20, :critical_value=>37.566},
 {:df=>21, :critical_value=>38.932},
 {:df=>22, :critical_value=>40.289},
 {:df=>23, :critical_value=>41.638},
 {:df=>24, :critical_value=>42.98},
 {:df=>25, :critical_value=>44.314},
 {:df=>26, :critical_value=>45.642},
 {:df=>27, :critical_value=>46.963},
 {:df=>28, :critical_value=>48.278},
 {:df=>29, :critical_value=>49.588},
 {:df=>30, :critical_value=>50.892},
 {:df=>40, :critical_value=>63.691},
 {:df=>50, :critical_value=>76.154},
 {:df=>60, :critical_value=>88.379},
 {:df=>70, :critical_value=>100.425},
 {:df=>80, :critical_value=>112.329},
 {:df=>90, :critical_value=>124.116},
 {:df=>100, :critical_value=>135.807}]