Tuesday, August 02, 2005

standard error(標準誤)

  • 標準誤相當於統計母群的標準差。其公式隨統計項目不同而異。例如:樣本平均的標準誤=樣本的標準差/根號(樣本大小)。The standard error is the estimated standard deviation of a statistic. The formula depends on what statistic you are talking about. For example, the standard error of a sample mean is just the sample standard deviation divided by the square root of the sample size.

http://www.cmh.edu/stats/definitions/stderr.htm

  • 標準誤。如果我們從同個母群中取出多個樣本,那我們必然可得到多個樣本數值的平均。若我們計算這些樣本數平均相對於未知母群平均的標準差,即稱為「標準誤」。標準誤是用來測量樣本平均的變異性。然而,我們可以用以下公式來計算標準誤:(即不需用到未知的母群平均) 標準誤 = 標準差/根號(樣本數-1)。Standard error. If we took several samples of the same thing we would, of course, be able to compute several means, one for each sample. If we computed the standard deviation of these sample means as an estimate of their variation around the true but unknown population mean, that standard deviation of means is called the standard error. Standard error measures the variability of sample means. However, since we normally have only one sample but still wish to assess its variability, we can compute estimated standard error by this formula:


SE = sd/SQRT(n - 1)


where sd is the standard deviation for a variable and n is sample size. Often estimated standard error is just called 'standard error.'

http://www2.chass.ncsu.edu/garson/pa765/normal.htm

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