Class: Cucloud::Utilities

Inherits:
Object
  • Object
show all
Defined in:
lib/cucloud/utilities.rb

Overview

Utilities class - for basice shared utilities

Constant Summary collapse

Z_SCORE_99 =

Z Score to calculate 99% confidence interval

2.576
Z_SCORE_96 =

Z Score to calculate 99% confidence interval

1.96

Class Method Summary collapse

Class Method Details

.confidence_interval(mean, stdev, sample_size, zscore) ⇒ Array

Calculate confidence interval for given zscore

Parameters:

  • mean (Float) —

    sample mean

  • stdev (Float) —

    sample standard deviation

  • sample_size (Integer) —

    sample size

Returns:

  • (Array) —

    Two element array representing the computed confidence interval



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# File 'lib/cucloud/utilities.rb', line 34

def self.confidence_interval(mean, stdev, sample_size, zscore)
  delta = zscore * stdev / Math.sqrt(sample_size - 1)
  [mean - delta, mean + delta]
end

.confidence_interval_95(mean, stdev, sample_size) ⇒ Array

Calculate 95% confidence interval

Parameters:

  • mean (Float) —

    sample mean

  • stdev (Float) —

    sample standard deviation

  • sample_size (Integer) —

    sample size

Returns:

  • (Array) —

    Two element array representing the computed confidence interval



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# File 'lib/cucloud/utilities.rb', line 23

def self.confidence_interval_95(mean, stdev, sample_size)
  confidence_interval(mean, stdev, sample_size, Z_SCORE_96)
end

.confidence_interval_99(mean, stdev, sample_size) ⇒ Array

Calculate 99% confidence interval

Parameters:

  • mean (Float) —

    sample mean

  • stdev (Float) —

    sample standard deviation

  • sample_size (Integer) —

    sample size

Returns:

  • (Array) —

    Two element array representing the computed confidence interval



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# File 'lib/cucloud/utilities.rb', line 14

def self.confidence_interval_99(mean, stdev, sample_size)
  confidence_interval(mean, stdev, sample_size, Z_SCORE_99)
end