Directional measures for Store by Service satisfaction, controlling for Contact
Directional measures quantify the reduction in the error of predicting the row variable value when you know the column variable value, or vice versa. Each measure simply has a different definition of "error." Lambda defines error as the misclassification of cases, and cases are classified according to the modal (most frequent) category. Tau defines error as the misclassification of a case, and cases are classified into category j with probability equal to the observed frequency of category j. The uncertainty coefficient defines error as the entropy, or P(category j) * ln(P(category j)) summed over the categories of the variable. The uncertainty coefficient is also known as Theil's U. For customers who had contact, the Goodman and Kruskal's tau value of 0.031 with Store dependent means that there is a 3.1% reduction in misclassification. The other measures report equally small values, indicating that the association between Store and Service satisfaction is almost solely due to the poor service at store 2.