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- Topic: sample standard deviation df

Author | Topic: sample standard deviation df |
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77baby@2015-01-15 14:31:49 |
Remember that you are interested in finding descriptive statistics for the r.v. X. This means that when estimating sample standard deviation you must rely on xbar or the sample mean. Because you are using this estimated parameter to estimate sigma you must subtract one from the df. This is why df=n-1. The same will hold when looking at a linear regression problem, look at the number of parameters you are estimating and subtract them from the sample size. There is a lot more detail that can be discussed, but this is the main idea. |