Use an interval plot to:

·    Display sample means

·    Visually represent confidence intervals for the mean

·    Compare group means

Minitab plots the sample mean for each group along with a range of likely values for the population mean.

A forest products laboratory tested the effect of temperature in the production of plywood. To make plywood, chucks are inserted at each end of a log. Then, the log spins while a saw blade cuts off a thin layer of wood. These layers are glued together to form plywood. The laboratory measured the maximum torque that could be applied to the chucks before they spun out of the log at three temperatures.

Data: Plywood.MTW (available in the Sample Data folder).