Student's t Distribution
Student's t distribution is a bell-shaped continuous probability distribution function that is centered on zero and parameterized to degrees of freedom.
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Description
When working with normally distributed data where the sample variance is not an appropriate estimator for population variance, Student's t distribution is more appropriate. The distribution has fatter tails and is effectively a more conservative fit to normal data. More formally, the variance is greater than 1 but converges to 1 as the sample size (n) grows.
The probability density function is given as:
where Γ(.) is the gamma function and d is the number of degrees of freedom (i.e., n - 1).