Figure 9. Balanced and unbalanced data.

(a) In this toy example there are two task parameters (factors), with two possible values each. Parameter A (left) is represented by the size of the dot, parameter B (middle) is represented by the color of the dot, noise is Gaussian with zero mean and zero correlation (right). Interaction term is equal to zero. (b) Balanced case with $N=10$ data points in each of the four parameter combinations. Overall correlation is zero. (c) Unbalanced case with $N=10$ for two parameter combinations and $N=100$ for the other two. Overall correlation is 0.8.

DOI: http://dx.doi.org/10.7554/eLife.10989.014