Module: Experiment::Stats::Descriptive

Included in:
Experiment::Stats
Defined in:
lib/experiment/stats/descriptive.rb

Instance Method Summary collapse

Instance Method Details

#mean(ar = self) ⇒ Object 



30
31
32
 
# File 'lib/experiment/stats/descriptive.rb', line 30

def mean(ar = self)
  sum(ar) / ar.count
end

#median(ar = self) ⇒ Object 



34
35
36
37
38
39
40
41
 
# File 'lib/experiment/stats/descriptive.rb', line 34

def median(ar = self)
a = ar.sort
if ar.count.odd?
	a[(ar.count-1)/2]
else
	(a[ar.count/2 - 1] + a[ar.count/2]) / 2.0
end
end

#range(ar = self) ⇒ Object 



26
27
28
 
# File 'lib/experiment/stats/descriptive.rb', line 26

def range(ar = self)
	ar.max - ar.min
end

#standard_deviation(ar = self) ⇒ Object 



14
15
16
 
# File 'lib/experiment/stats/descriptive.rb', line 14

def standard_deviation(ar = self)
  Math.sqrt(variance(ar))
end

#sum(ar = self, &block) ⇒ Object 



5
6
7
 
# File 'lib/experiment/stats/descriptive.rb', line 5

def sum(ar = self, &block)
ar.reduce(0.0) {|asum, a| (block_given? ? yield(a) : a) + asum}
end

#variance(ar = self) ⇒ Object 



9
10
11
12
 
# File 'lib/experiment/stats/descriptive.rb', line 9

def variance(ar = self)
  v = sum(ar) {|x| (mean(ar) - x)**2.0 }
   v/(ar.count - 1.0)
end

#z_score(ar = self, x) ⇒ Object 



22
23
24
 
# File 'lib/experiment/stats/descriptive.rb', line 22

def z_score(ar = self, x)
  (x - mean(ar)) / standard_deviation(ar)
end

#z_scores(ar = self) ⇒ Object 



18
19
20
 
# File 'lib/experiment/stats/descriptive.rb', line 18

def z_scores(ar = self)
  ar.map {|x| z_score(ar, x)}
end