I want to do the following with some time series data:

Calculate 95% confidence interval for mean defined as +/-sigma(x)qt(0.025, 
N*-1) / sqrt(N*) where sigma(x) is the standard deviation at any point x 
and qt(0.025, N*-1) is the 2.5 percentage point of the Student-t 
distribution with N*-1 degrees of freedom.

I have been trying to do this with HypothesisTests' ci() and 
OneSampleTTest() functions, but as far as I can see OneSampleTTest() does 
not allow me to choose the number of degrees of freedom.

julia> t = OneSampleTTest(arr)
One sample t-test
-----------------
Population details:
    parameter of interest:   Mean
    value under h_0:         0
    point estimate:          0.3835
    95% confidence interval: (0.14217301685460967,0.6248269831453903)

Test summary:
    outcome with 95% confidence: reject h_0
    two-sided p-value:           0.0057946078675091515 (very significant)

Details:
    number of observations:   10
    t-statistic:              3.5948622927526235
    degrees of freedom:       9
    empirical standard error: 0.10668002520517972


julia> t.df
9
julia> ci(t, 0.025, tail=:both)
(0.09706297518543938,0.6699370248145606)


Can anybody point me in the right direction?



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