Matrix questions are perfect for collecting a large amount of data through a concise interface. A matrix is a series of choice questions that all have the same choices, shown in a grid-like layout.
The right matrix for the right occasion...
A simple matrix would be a single selection matrix as shown here. But there are also multi-selection matrix questions, and even dual-range matrix questions.
Powerful content and formatting options
Comments can be added for each row in the matrix, and can even be hidden unless a certain answer is entered. Formatting extends to how column headings are shown, and even whether rows and columns should be "flipped".