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18

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How Do I Find The Standard Error Of The Mean (sem) And Variance? Please Help?

admin    SEM     Error, Find, Help, Mean, Please, Standard, Variance

Hey everyone, I am having a hard time with doing my chemistry calculations. I think I understand how to find the SEM, but the variance confuses me. (Like, how do you get the number in front of your value that has a + or – above one another) Thanks a lot for the help and I really appreciate it.

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1 Comment to “How Do I Find The Standard Error Of The Mean (sem) And Variance? Please Help?”

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  coolblue January 18, 2010 at 4:42 pm

  SEM = standard deviation divided by the square root of n, where n is the sample size. Variance is the square of the standard deviation.
  If the variance is 64, for example, the standard deviation is 8.
  If you have a set of data, you can compute the mean and the standard deviation.
  Here is an example.
  The data : 4,6,8,10
  Number of cases 4
  To find the mean, add all of the observations and divide by 4
  Mean 7
  Squared deviations
  (4-7)^2 = (-3)^2 = 9
  (6-7)^2 = (-1)^2 = 1
  (8-7)^2 = (1)^2 = 1
  (10-7)^2 = (3)^2 = 9
  Add the squared deviations and divide by 4
  Variance = 20/4
  Variance 5
  Standard deviation = sqrt(variance) = 2.2361
  SEM = 2.2361 / 2 =1.11805