Created
December 10, 2012 03:51
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Statistics mean / variance
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta http-equiv="Content-Type" content="text/html;charset=utf-8"/> | |
| <style type="text/css"> | |
| body { | |
| font: 300 13px "Helvetica Neue", Helvetica; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <script type="text/javascript"> | |
| var arr = [1, 2, 3, 5, 10, 25]; | |
| var arrLength = arr.length; | |
| var total = 0; | |
| var mean; | |
| var varianceTotal = 0; | |
| var biasedVariance = 0; | |
| var unbiasedVariance = 0; | |
| // array | |
| document.write("array: " + arr + "<br>"); | |
| // array length | |
| document.write("arrLength: " + arrLength + "<br>"); | |
| // total | |
| for (var i = 0; i < arrLength; i++) { | |
| total += arr[i]; | |
| } | |
| document.write("total: " + total + "<br>"); | |
| // mean | |
| mean = parseFloat(total / arrLength).toFixed(2); | |
| document.write("<strong>mean:</strong> " + mean + "<br>"); | |
| // sample variance total | |
| for (var i = 0; i < arrLength; i++) { | |
| var square; | |
| var squareSum; | |
| squareSum = (arr[i] - mean); | |
| square = squareSum * squareSum; | |
| square = parseFloat(square).toFixed(2); | |
| varianceTotal = parseFloat(varianceTotal) + parseFloat(square); | |
| document.write("square " + i + ": " + square + "<br>"); | |
| } | |
| varianceTotal = parseFloat(varianceTotal).toFixed(2); | |
| document.write("variance total: " + varianceTotal + "<br>"); | |
| // biased variance (population) | |
| biasedVariance = (varianceTotal / arrLength); | |
| biasedVariance = parseFloat(biasedVariance).toFixed(2); | |
| document.write("<strong>biased variance (population):</strong> " + biasedVariance + "<br>"); | |
| // unbiased variance (sample) | |
| unbiasedVariance = (varianceTotal / (arrLength - 1)); | |
| unbiasedVariance = parseFloat(unbiasedVariance).toFixed(2); | |
| document.write("<strong>unbiased variance (sample):</strong> " + unbiasedVariance + "<br>"); | |
| </script> | |
| </body> | |
| </html> |
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