Where:
"Jason" = 2, "Judah" = 3, "Allison" = 1, "Teresa" = 1, "Michelle" = 1?

names = ["Jason", "Jason", "Teresa", "Judah", "Michelle", "Judah", "Judah", "Allison"]
counts = Hash.new(0)
names.each { |name| counts[name] += 1 }
# => {"Jason" => 2, "Teresa" => 1, ....

names.inject(Hash.new(0)) { |total, e| total[e] += 1 ;total}

{"Jason"=>2, "Teresa"=>1, "Judah"=>3, "Michelle"=>1, "Allison"=>1}

names = ["Jason", "Jason", "Teresa", "Judah", "Michelle", "Judah", "Judah", "Allison"]
counts = {}
names.group_by(&:itself).each { |k,v| counts[k] = v.length }
# counts > {"Jason"=>2, "Teresa"=>1, "Judah"=>3, "Michelle"=>1, "Allison"=>1}

Multiset.new(*names)

require 'multiset'

names = %w[Jason Jason Teresa Judah Michelle Judah Judah Allison]

histogram = Multiset.new(*names)
# => #<Multiset: {"Jason", "Jason", "Teresa", "Judah", "Judah", "Judah", "Michelle", "Allison"}>

histogram.multiplicity('Judah')
# => 3

require 'multiset'

names = %w[Jason Jason Teresa Judah Michelle Judah Judah Allison]

histogram = Multiset[*names]
# => #<Multiset:#2 'Jason', #1 'Teresa', #3 'Judah', #1 'Michelle', #1 'Allison'>

names.each_with_object(Hash.new(0)) { |name, hash| hash[name] += 1}

=> {"Jason"=>2, "Teresa"=>1, "Judah"=>3, "Michelle"=>1, "Allison"=>1}

arr = ["Jason", "Jason", "Teresa", "Judah", "Michelle", "Judah", "Judah", "Allison"]
result = {}
arr.uniq.each{|element| result[element] = arr.count(element)}

array_with_lower_case_a = ["Jason", "Jason", "Teresa", "Judah", "Michelle", "Judah", "Judah", "Allison"]
hash_grouped_by_name = array_with_lower_case_a.group_by {|name| name}
hash_grouped_by_name.map{|name, names| [name, names.length]}
=> [["Jason", 2], ["Teresa", 1], ["Judah", 3], ["Michelle", 1], ["Allison", 1]]

another_array_with_lower_case_a = ["Jason", "jason", "Teresa", "Judah", "Michelle", "Judah Ben-Hur", "JUDAH", "Allison"]
hash_grouped_by_first_name = another_array_with_lower_case_a.group_by {|name| name.split(" ").first.capitalize}
hash_grouped_by_first_name.map{|first_name, names| [first_name, names.length]}
=> [["Jason", 2], ["Teresa", 1], ["Judah", 3], ["Michelle", 1], ["Allison", 1]]

names = ["Jason", "Jason", "Teresa", "Judah", "Michelle", "Judah", "Judah", "Allison"]
Hash[names.group_by{|i| i }.map{|k,v| [k,v.size]}]
# => {"Jason"=>2, "Teresa"=>1, "Judah"=>3, "Michelle"=>1, "Allison"=>1}

a = [1, 2, 3, 2, 5, 6, 7, 5, 5]
a.each_with_object(Hash.new(0)) { |o, h| h[o] += 1 }

# => {1=>1, 2=>2, 3=>1, 5=>3, 6=>1, 7=>1}

C:Documents and Settingsa.grimm>irb
irb(main):001:0> Array = nil
(irb):1: warning: already initialized constant Array
=> nil
C:/Ruby19/lib/ruby/site_ruby/1.9.1/rbreadline.rb:3177:in `rl_redisplay': undefined method `new' for nil:NilClass (NoMethodError)
        from C:/Ruby19/lib/ruby/site_ruby/1.9.1/rbreadline.rb:3873:in `readline_internal_setup'
        from C:/Ruby19/lib/ruby/site_ruby/1.9.1/rbreadline.rb:4704:in `readline_internal'
        from C:/Ruby19/lib/ruby/site_ruby/1.9.1/rbreadline.rb:4727:in `readline'
        from C:/Ruby19/lib/ruby/site_ruby/1.9.1/readline.rb:40:in `readline'
        from C:/Ruby19/lib/ruby/1.9.1/irb/input-method.rb:115:in `gets'
        from C:/Ruby19/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_input'
        from C:/Ruby19/lib/ruby/1.9.1/irb.rb:271:in `signal_status'
        from C:/Ruby19/lib/ruby/1.9.1/irb.rb:138:in `block in eval_input'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:189:in `call'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:189:in `buf_input'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:103:in `getc'
        from C:/Ruby19/lib/ruby/1.9.1/irb/slex.rb:205:in `match_io'
        from C:/Ruby19/lib/ruby/1.9.1/irb/slex.rb:75:in `match'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:287:in `token'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:263:in `lex'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:234:in `block (2 levels) in each_top_level_statement'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:230:in `loop'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:230:in `block in each_top_level_statement'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `catch'
        from C:/Ruby19/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `each_top_level_statement'
        from C:/Ruby19/lib/ruby/1.9.1/irb.rb:153:in `eval_input'
        from C:/Ruby19/lib/ruby/1.9.1/irb.rb:70:in `block in start'
        from C:/Ruby19/lib/ruby/1.9.1/irb.rb:69:in `catch'
        from C:/Ruby19/lib/ruby/1.9.1/irb.rb:69:in `start'
        from C:/Ruby19/bin/irb:12:in `<main>'

C:Documents and Settingsa.grimm>

arr = ["Jason", "Jason", "Teresa", "Judah", "Michelle", "Judah", "Judah", "Allison"]

arr.uniq.inject({}) {|a, e| a.merge({e => arr.count(e)})}

names = ["Jason", "Jason", "Teresa", "Judah", "Michelle", "Judah", "Judah", "Allison"]

name_frequency_hash = {}

names.each do |name|
  count = names.count(name)
  name_frequency_hash[name] = count
end
#=> {"Jason"=>2, "Teresa"=>1, "Judah"=>3, "Michelle"=>1, "Allison"=>1}