Let’s walk through an invented research example to better understand how the standard normal distribution works.Īs a sleep researcher, you’re curious about how sleep habits changed during COVID-19 lockdowns. Step-by-step example of using the z distribution That means it’s likely that only 6.3% of SAT scores in your sample exceed 1380. Position or shape (relative to standard normal distribution)
A small standard deviation results in a narrow curve, while a large standard deviation leads to a wide curve. The standard deviation stretches or squeezes the curve. Increasing the mean moves the curve right, while decreasing it moves the curve left. The mean determines where the curve is centered. In the standard normal distribution, the mean and standard deviation are always fixed.Įvery normal distribution is a version of the standard normal distribution that’s been stretched or squeezed and moved horizontally right or left.
However, a normal distribution can take on any value as its mean and standard deviation. Normal distribution vs the standard normal distributionĪll normal distributions, like the standard normal distribution, are unimodal and symmetrically distributed with a bell-shaped curve.
