The best performance of an individual that aligns with company"s strategy. Range the difference between the highest and lowest scores. Standard deviation computed measure of how much scores vary around the mean. We need to correlate our selection system with performance on the job: relationship between two variables smoking and cancer, does not imply one variable causes another ice cream sales higher, crime higher. Correlates with weather, doesn"t mean they cause each other: correlation coefficient (r) - ranges from -1 to +1 : -0. 9 strong negative correlation, +0. 9 strong positive correlation. Positive correlation a relationship between 2 variables where as one variable increases, so does the other. Negative correlation a relationship between 2 variables where as one variable increases, the other decreases. As number of children you have increases, satisfaction with marriage, job and life decreases. Reliability - the degree to which measurements are free from random measurement errors.