Degrees of freedom
Why did you choose a 9 degrees of freedom?its similar to the level of confidence most comun ?
2 answers ( 0 marked as helpful)
degrees of freedom = sample size - 1
As the above points out, in short its becasue of the formula. In a longer explanation its because of something like if you know the sample mean, then you only need to know the values of the 9 out of 10 of the other values. This means you can work out the 10th value with the information provided.