Training evaluation involves assessing the effectiveness of training programs in terms of benefits to trainees and the company. It is important for companies to understand the usefulness of training given the significant costs. Evaluation determines if employees were satisfied, learned important skills, and can apply what they learned. Evaluation design can be a time series comparing pre- and post-training performance, or a controlled experiment comparing the performance of a training group to a control group. Evaluation measures reaction, learning, behavior change, and results to determine a program's effectiveness.