Swimming performance is assessed to the closest 0.01 second, with the top 15 swimmers separated by less than 0.10 second. Given this, it should come as no surprise that swimmers are always seeking for ways to improve their performance. The best way to do so is through training, but not all training methods are created equal. Some work better than others, depending on what type of swimmer you are and what goals you want to achieve. The most common way to measure swimming performance is through times. These times can either be based on a specific distance (i.e., 100-meter free time trial) or the length of an event (i.e., 400-yard individual medley). Times can also be classified as absolute or relative. Absolute times are calculated from the start to finish of the race, while relative times account for the position of each swimmer at any point during the race. For example, if one swimmer finishes a race more than another, they will usually have a longer relative time even though they finished the race in exactly the same amount of time as the other swimmer. Another method for measuring swimming performance is through splits. This can be done either visually or electronically. With visual splits, each swimmer will signal when they reach certain points during the race. These signals can be flags or lights.