The t-distribution is similar to the normal distribution, with its bell shape, but it has heavier tails. It is used for estimating population parameters for small sample sizes or unknown variances.

will be much closer to a normal distribution curve. Smaller sample sizes will correspond with smaller degrees of freedom and result in fatter t-distribution tails. In the examples above ...

A normal distribution curve will therefore not be a good description of phenomena that have more frequent extreme outcomes or asymmetrical deviations from the mean. Such distributions with a greater ...