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  1. Commons Math
  2. MATH-1398

Support simple Arithmetic mean without Compute correction factor in second pass?

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    • Type: Improvement
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: 4.X
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      Description

      The mean calculate by this function is different excel. which just sum/n as first half of function. can we provide another option to calculate normal means?

      org.apache.commons.math3.stat.descriptive.moment.Mean

      public double evaluate(final double[] values,final int begin, final int length)
      163 throws MathIllegalArgumentException {
      164 if (test(values, begin, length)) {
      165 Sum sum = new Sum();
      166 double sampleSize = length;
      167
      168 // Compute initial estimate using definitional formula
      169 double xbar = sum.evaluate(values, begin, length) / sampleSize;
      170
      171 // Compute correction factor in second pass
      172 double correction = 0;
      173 for (int i = begin; i < begin + length; i++)

      { 174 correction += values[i] - xbar; 175 }

      176 return xbar + (correction/sampleSize);
      177 }
      178 return Double.NaN;
      179 }

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            • Assignee:
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              Reporter:
              francis.li Francis Li
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              • Created:
                Updated: