Critical IncidentsCritical incidents are essay descriptions of the times when a trainee does something especially good or especially bad. These descriptions are typically accumulated in an employee's personal file. They are often used to evaluate an employee's performance, and they can also be used to evaluate the success of a training program.observationsSome training programs can only be assessed by observing the behavior of employees to discover whether they are behaving differently after training or if the training has solved the problems. The disadvantage of observations is that they are an intrusive type of measure. The process of observing an employee’s performance often causes the employee to behave differently. (This phenomenon is called the Hawthorne Effect" after the Hawthorne studies 1924-1934 ). Most employees tend to work faster when they know they are being observed and their productivity is being measured. However, other employees intentionally alter their performance to create meaningless data.