81 lines
1.3 KiB
Markdown
81 lines
1.3 KiB
Markdown
# Statistic
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Selected statistical methods.
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## Correlation
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Correlation coefficients are used in statistics to measure how strong a relationship is between two variables. There are several types of correlation coefficient.
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### Pearson correlation
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Pearson’s correlation or Pearson correlation is a correlation coefficient commonly used in linear regression.
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Example:
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```
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use Phpml\Math\Statistic\Correlation;
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$x = [43, 21, 25, 42, 57, 59];
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$y = [99, 65, 79, 75, 87, 82];
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Correlation::pearson($x, $y);
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// return 0.549
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```
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## Mean
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### Arithmetic
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Example:
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```
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use Phpml\Math\Statistic\Mean;
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Mean::arithmetic([2, 5];
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// return 3.5
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Mean::arithmetic([0.5, 0.5, 1.5, 2.5, 3.5];
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// return 1.7
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```
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## Median
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Example:
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```
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use Phpml\Math\Statistic\Mean;
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Mean::median([5, 2, 6, 1, 3, 4]);
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// return 3.5
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Mean::median([5, 2, 6, 1, 3]);
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// return 3
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```
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## Mode
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Example:
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```
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use Phpml\Math\Statistic\Mean;
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Mean::mode([5, 2, 6, 1, 3, 4, 6, 6, 5]);
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// return 6
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```
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## Standard Deviation
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Example:
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```
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use Phpml\Math\Statistic\StandardDeviation;
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$population = [5, 6, 8, 9];
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StandardDeviation::population($population)
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// return 1.825
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$population = [7100, 15500, 4400, 4400, 5900, 4600, 8800, 2000, 2750, 2550, 960, 1025];
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StandardDeviation::population($population)
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// return 4079
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```
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