As it was previously mentioned, we use T-distribution for the samples drawn from an
abnormally distributed population or with samples of size smaller than thirty. We present
the equations to calculate the t-scores as well as the limits for the confidence interval.
T-distribution can be used to calculate the confidence interval for sampling distribution
drawn from abnormally distributed population or samples of size less than thirty. When
sampling distribution is used involving many samples, the t-score can be calculated by:
T-distribution has always a mean of zero. The variance of a t-distribution depends on its
degrees of freedom. The degree of freedom (d.f.) is always greater than or equal to two.
The variance of a t-distribution is calculated by
When there are multiple degrees of freedom, the variance is always greater than one even
though its value is near one. The t-distribution is symmetry. However, the tails of a t-