Figure 9-1

The Wider and Flatter t Distributions For smaller samples, the t distributions are wider and flatter than the z distribution. As the sample size increases, however, the t distributions approach the shape of the z distribution. For instance, in this figure, the t distribution most similar to the z distribution is that for a sample of 30 individuals. This makes sense because a distribution derived from a larger sample size would be more likely to be similar to that of the entire population than one derived from a smaller sample size.